N-acyl-(3-substituted)-(8-methyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazines as selective NK-3 receptor antagonists, pharmaceutical composition, methods for use in NK-3 receptor-mediated disorders

ABSTRACT

Novel compounds of Formula I 
                         
methods of manufacturing the compounds and their use in therapeutic treatments are presented.

FIELD OF INVENTION

The present invention relates to novelN-acyl-(3-substituted)-(8-methyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazinesincluding their pharmaceutically acceptable solvates that are selectiveantagonists to neurokinin-3 receptor (NK-3) and are useful astherapeutic compounds, particularly in the treatment and/or preventionof a broad array of CNS and peripheral diseases or disorders.

BACKGROUND OF INVENTION

Tachykinin receptors are the targets of a family of structurally relatedpeptides which include substance P (SP), neurokinin A (NKA) andneurokinin B (NKB), named collectively “tachykinins”. Tachykinins aresynthesized in the central nervous system (CNS) and peripheral tissues,where they exert a variety of biological activities. Three tachykininreceptors are known which are named neurokinin-1 (NK-1), neurokinin-2(NK-2) and neurokinin-3 (NK-3) receptors. Tachykinin receptors belong tothe rhodopsin-like seven membrane G-protein coupled receptors. SP hasthe highest affinity and is believed to be the endogenous ligand ofNK-1, NKA for NK-2 receptor and NKB for NK-3 receptor, althoughcross-reactivity amongst these ligands does exist. The NK-1, NK-2 andNK-3 receptors have been identified in different species. NK-1 and NK-2receptors are expressed in a wide variety of peripheral tissues and NK-1receptors are also expressed in the CNS; whereas NK-3 receptors areprimarily expressed in the CNS.

The neurokinin receptors mediate a variety of tachykinin-stimulatedbiological effects that include transmission of excitatory neuronalsignals in the CNS and periphery (e.g. pain), modulation of smoothmuscle contractile activity, modulation of immune and inflammatoryresponses, induction of hypotensive effects via dilatation of theperipheral vasculature and stimulation of endocrine and exocrine glandsecretions.

In the CNS, the NK-3 receptor is expressed in regions including themedial prefrontal cortex, the hippocampus, the thalamus and theamygdala. Moreover, NK-3 receptors are expressed on dopaminergicneurons. Activation of NK-3 receptors has been shown to modulatedopamine, acetylcholine and serotonin release suggesting a therapeuticutility for NK-3 receptor modulators for the treatment of a variety ofdisorders including psychotic disorders, anxiety, depression,schizophrenia as well as obesity, pain or inflammation (Giardina et al.,Exp. Opinion Ther. Patents, 2000, 10(6), 939-960; Current Opinion inInvestigational Drugs, 2001, 2(7), 950-956 and Dawson and Smith, CurrentPharmaceutical Design, 2010, 16, 344-357).

Schizophrenia is classified into subgroups. The paranoid type ischaracterized by delusions and hallucinations and absence of thoughtdisorder, disorganized behavior, and affective flattening. In thedisorganized type, which is also named ‘hebephrenic schizophrenia’ inthe International Classification of Diseases (ICD), thought disorder andflat affect are present together. In the catatonic type, prominentpsychomotor disturbances are evident, and symptoms may include catatonicstupor and waxy flexibility. In the undifferentiated type, psychoticsymptoms are present but the criteria for paranoid, disorganized, orcatatonic types have not been met. The symptoms of schizophrenianormally manifest themselves in three broad categories, i.e. positive,negative and cognitive symptoms. Positive symptoms are those, whichrepresent an “excess” of normal experiences, such as hallucinations anddelusions. Negative symptoms are those where the patient suffers from alack of normal experiences, such as anhedonia and lack of socialinteraction. The cognitive symptoms relate to cognitive impairment inschizophrenics, such as a lack of sustained attention and deficits indecision making. The current antipsychotic drugs (APDs) are fairlysuccessful in treating the positive symptoms but fare less well for thenegative and cognitive symptoms. Contrary to that, NK-3 antagonists havebeen shown clinically to improve on both positive and negative symptomsin schizophrenics (Meltzer et al, Am. J. Psychiatry, 2004, 161, 975-984)and ameliorate cognitive behavior of schizophrenics (Curr. Opion.Invest. Drug, 2005, 6, 717-721).

In rat, morphological studies provide evidence for putative interactionsbetween NKB neurons and the hypothalamic reproductive axis (Krajewski etal, J. Comp. Neurol., 2005, 489(3), 372-386). In arcuate nucleusneurons, NKB expression co-localizes with estrogen receptor α anddynorphin, implicated in progesterone feedback to Gonadotropin ReleasingHormone (GnRH) secretion (Burke et al., J. Comp. Neurol., 2006, 498(5),712-726; Goodman et al., Endocrinology, 2004, 145(6), 2959-2967).Moreover, NK-3 receptor is highly expressed in the hypothalamic arcuatenucleus in neurons which are involved in the regulation of GnRH release.

WO 00/43008 discloses a method of suppressing gonadotropin and/orandrogen production with specific NK-3 receptor antagonists. Moreparticularly, the WO 00/43008 application relates to loweringluteinizing hormone (LH) blood level by administering an NK-3 receptorantagonist. Concurrently or alternatively with gonadotropin suppression,WO 00/43008 also relates to suppression of androgen production with NK-3receptor antagonists. Recently it has been postulated that NKB actsautosynaptically on kisspeptin neurons in the arcuate nucleus tosynchronize and shape the pulsatile secretion of kisspeptin and drivethe release of GnRH from fibers in the median eminence (Navarro et al.,J. of Neuroscience, 2009, 23(38), 11859-11866). All these observationssuggest a therapeutic utility for NK-3 receptor modulators for sexhormone-dependent diseases.

NK-3 receptors are also found in the human myenteric and submucosalplexus of the sigmoid colon as well as in the gastric fundus (Dassetal., Gastroenterol., 2002, 122 (Suppl 1), Abstract M1033) withparticular expression noted on myenteric intrinsic primary afferentneurons (IPANs) (Lomax and Furness, Cell Tissue Res, 2000, 302, 59-3).Intense stimulation of IPANs changes patterns of intestinal motility andintestinal sensitivity. Electrophysiology experiments have shown thatactivation of the NK-3 receptor changes the voltage threshold of actionpotentials in IPANs and promotes the generation of long-lasting plateaupotentials (Copel et al., J Physiol, 2009, 587, 1461-1479) that maysensitize these neurons to mechanical and chemical stimuli leading toeffects on gut motility and secretion. Similarly, Irritable BowelSyndrome (IBS) is characterized by patient hypersensitivity tomechanical and chemical stimuli. Thus, NK-3 antagonists have been testedin preclinical models of IBS where they have been shown to be effectiveto reduce nociceptive behavior caused by colo-rectal distension(Fioramonti et al., Neurogastroenterol Motil, 2003, 15, 363-369; Shaftonet al., Neurogastroenterol Motil, 2004, 16, 223-231) and, on this basis,NK-3 antagonists have been advanced into clinical development for thetreatment of IBS (Houghton et al., Neurogastroenterol Motil, 2007, 19,732-743; Dukes et al., Gastroenterol, 2007, 132, A60).

Non-peptide antagonists have been developed for each of the tachykininreceptors. Some of them have been described as dual modulators able tomodulate both NK-2 and NK-3 receptors (WO 06/120478). However, knownnon-peptide NK-3 receptor antagonists suffer from a number of drawbacks,notably poor safety profile and limited CNS penetrability that may limitthe success of these compounds in clinical development.

On this basis, new potent and selective antagonists of NK-3 receptor maybe of therapeutic value for the preparation of drugs useful in thetreatment and/or prevention of CNS and peripheral diseases or disordersin which NKB and the NK-3 receptors are involved.

Target potency alone, which may be demonstrated by competitive bindingdata, is not sufficient for drug development. Rather, efficacy in vivois contingent upon achieving a relevant “free” drug concentrationrelative to the target potency at the physiological site of action. Drugmolecules typically bind reversibly to proteins and lipids in plasma.The “free” fraction refers to the drug concentration that is unbound andtherefore available to engage the biological target and elicitpharmacological activity. This free fraction is commonly determinedusing plasma protein binding (PPB) assays. The free drug fraction isrelevant to not only achieving the desired pharmacological activity, butalso potentially undesirable activities including rapid hepaticmetabolism (leading to high first-pass clearance and thereby poor oralbioavailability) as well as possible off-target activities that can leadto safety concerns (for example, inhibition of hERG ion channelactivity, a widely accepted marker of cardiovascular toxicity).

The invention thus encompasses compounds of general Formula I, theirpharmaceutically acceptable solvates as well as methods of use of suchcompounds or compositions comprising such compounds as antagonists tothe NK-3 receptor. Compounds of Formula I areN-acyl-(3-substituted)-(8-methyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazines.The compounds of the invention are generally disclosed in internationalpatent application WO2011/121137 but none is specifically exemplifiedtherein. On another hand, unsubstituted and thus non-chiral5,6,7,8-tetrahydro[1,2,4]triazolo[4,3-a]pyrazines have been disclosed inWO2010/125102 as modulators of an unrelated target, namely P2X7.

SUMMARY

In a general aspect, the invention provides compounds of general FormulaI:

-   -   and pharmaceutically acceptable solvates thereof, wherein:    -   R¹ is H or F;    -   R^(1′) is H;    -   R² is H, F or Cl;    -   R^(2′) is H or F;    -   R³ is F or Cl;    -   R⁴ is methyl or trifluoromethyl;    -   X¹ is S and X² is N or X¹ is CH and X² is O;    -   represents a single or a double bound depending on X¹ and X²;    -   stands for the (R)-enantiomer or for the racemate of compound of        Formula I.

In another aspect, the present invention provides a pharmaceuticalcomposition comprising at least one compound according to the inventionor a pharmaceutically acceptable solvate thereof.

The invention also relates to the use of the above compounds or theirpharmaceutically acceptable solvates as modulators of NK-3 receptors,preferably as antagonists of NK-3 receptors.

The invention also relates to the use of the above compounds or theirpharmaceutically acceptable solvates as lowering agents of thecirculating LH levels.

The invention further provides methods of treatment and/or prevention ofdepression, anxiety, psychosis, schizophrenia, psychotic disorders,bipolar disorders, cognitive disorders, Parkinson's disease, Alzheimer'sdisease, attention deficit hyperactivity disorder (ADHD), pain,convulsion, obesity, inflammatory diseases including irritable bowelsyndrome (IBS) and inflammatory bowel disorders, emesis, pre-eclampsia,airway related diseases including chronic obstructive pulmonary disease,asthma, airway hyperresponsiveness, bronchoconstriction and cough,reproduction disorders, contraception and sex hormone-dependent diseasesincluding but not limited to benign prostatic hyperplasia (BPH),prostatic hyperplasia, metastatic prostatic carcinoma, testicularcancer, breast cancer, ovarian cancer, androgen dependent acne, malepattern baldness, endometriosis, abnormal puberty, uterine fibrosis,uterine fibroid tumor, hormone-dependent cancers, hyperandrogenism,hirsutism, virilization, polycystic ovary syndrome (PCOS), premenstrualdysphoric disease (PMDD), HAIR-AN syndrome (hyperandrogenism, insulinresistance and acanthosisnigricans), ovarian hyperthecosis (HAIR-AN withhyperplasia of luteinized theca cells in ovarian stroma), othermanifestations of high intraovarian androgen concentrations (e.g.follicular maturation arrest, atresia, anovulation, dysmenorrhea,dysfunctional uterine bleeding, infertility), androgen-producing tumor(virilizing ovarian or adrenal tumor), menorrhagia and adenomyosiscomprising the administration of a therapeutically effective amount of acompound or pharmaceutically acceptable solvate of Formula I, to apatient in need thereof. The invention further provides methods oftreatment and/or prevention of depression, anxiety, psychosis,schizophrenia, psychotic disorders, bipolar disorders, cognitivedisorders, Parkinson's disease, Alzheimer's disease, attention deficithyperactivity disorder (ADHD), pain, convulsion, obesity, inflammatorydiseases including irritable bowel syndrome (IBS) and inflammatory boweldisorders, emesis, pre-eclampsia, airway related diseases includingchronic obstructive pulmonary disease, asthma, airwayhyperresponsiveness, bronchoconstriction and cough, urinaryincontinence, reproduction disorders, contraception and sexhormone-dependent diseases including but not limited to benign prostatichyperplasia (BPH), prostatic hyperplasia, metastatic prostaticcarcinoma, testicular cancer, breast cancer, ovarian cancer, androgendependent acne, male pattern baldness, endometriosis, abnormal puberty,uterine fibrosis, uterine fibroid tumor, uterine leiomyoma,hormone-dependent cancers, hyperandrogenism, hirsutism, virilization,polycystic ovary syndrome (PCOS), premenstrual dysphoric disease (PMDD),HAIR-AN syndrome (hyperandrogenism, insulin resistance and acanthosisnigricans), ovarian hyperthecosis (HAIR-AN with hyperplasia ofluteinized theca cells in ovarian stroma), other manifestations of highintraovarian androgen concentrations (e.g. follicular maturation arrest,atresia, anovulation, dysmenorrhea, dysfunctional uterine bleeding,infertility), androgen-producing tumor (virilizing ovarian or adrenaltumor), menorrhagia and adenomyosis comprising the administration of atherapeutically effective amount of a compound or pharmaceuticallyacceptable solvate of Formula I, to a patient in need thereof.

Preferably the patient is a warm-blooded animal, more preferably ahuman.

The invention further provides methods of treatment for gynecologicaldisorders and infertility. In particular, the invention provides methodsto lower and/or suppress the LH-surge in assisted conception comprisingthe administration of a therapeutically effective amount of a compoundor pharmaceutically acceptable solvate of Formula I, to a patient inneed thereof. Preferably the patient is a warm-blooded animal, morepreferably a woman.

The invention further provides methods to affect androgen production tocause male castration and to inhibit the sex drive in male sexualoffenders comprising the administration of a therapeutically effectiveamount of a compound or pharmaceutically acceptable solvate of FormulaI, to a patient in need thereof. Preferably the patient is awarm-blooded animal, more preferably a man.

The invention also provides the use of a compound of Formula I or apharmaceutically acceptable solvate thereof as a medicament. Preferably,the medicament is used for the treatment and/or prevention ofdepression, anxiety, psychosis, schizophrenia, psychotic disorders,bipolar disorders, cognitive disorders, Parkinson's disease, Alzheimer'sdisease, attention deficit hyperactivity disorder (ADHD), pain,convulsion, obesity, inflammatory diseases including irritable bowelsyndrome (IBS) and inflammatory bowel disorders, emesis, pre-eclampsia,airway related diseases including chronic obstructive pulmonary disease,asthma, airway hyperresponsiveness, bronchoconstriction and cough,reproduction disorders, contraception and sex hormone-dependent diseasesincluding but not limited to benign prostatic hyperplasia (BPH),prostatic hyperplasia, metastatic prostatic carcinoma, testicularcancer, breast cancer, ovarian cancer, androgen dependent acne, malepattern baldness, endometriosis, abnormal puberty, uterine fibrosis,uterine fibroid tumor, hormone-dependent cancers, hyperandrogenism,hirsutism, virilization, polycystic ovary syndrome (PCOS), premenstrualdysphoric disease (PMDD), HAIR-AN syndrome (hyperandrogenism, insulinresistance and acanthosisnigricans), ovarian hyperthecosis (HAIR-AN withhyperplasia of luteinized theca cells in ovarian stroma), othermanifestations of high intraovarian androgen concentrations (e.g.follicular maturation arrest, atresia, anovulation, dysmenorrhea,dysfunctional uterine bleeding, infertility), androgen-producing tumor(virilizing ovarian or adrenal tumor), menorrhagia and adenomyosis.Preferably, the medicament is used for the treatment and/or preventionof depression, anxiety, psychosis, schizophrenia, psychotic disorders,bipolar disorders, cognitive disorders, Parkinson's disease, Alzheimer'sdisease, attention deficit hyperactivity disorder (ADHD), pain,convulsion, obesity, inflammatory diseases including irritable bowelsyndrome (IBS) and inflammatory bowel disorders, emesis, pre-eclampsia,airway related diseases including chronic obstructive pulmonary disease,asthma, airway hyperresponsiveness, bronchoconstriction and cough,urinary incontinence, reproduction disorders, contraception and sexhormone-dependent diseases including but not limited to benign prostatichyperplasia (BPH), prostatic hyperplasia, metastatic prostaticcarcinoma, testicular cancer, breast cancer, ovarian cancer, androgendependent acne, male pattern baldness, endometriosis, abnormal puberty,uterine fibrosis, uterine fibroid tumor, uterine leiomyoma,hormone-dependent cancers, hyperandrogenism, hirsutism, virilization,polycystic ovary syndrome (PCOS), premenstrual dysphoric disease (PMDD),HAIR-AN syndrome (hyperandrogenism, insulin resistance and acanthosisnigricans), ovarian hyperthecosis (HAIR-AN with hyperplasia ofluteinized theca cells in ovarian stroma), other manifestations of highintraovarian androgen concentrations (e.g. follicular maturation arrest,atresia, anovulation, dysmenorrhea, dysfunctional uterine bleeding,infertility), androgen-producing tumor (virilizing ovarian or adrenaltumor), menorrhagia and adenomyosis. The medicament may also be used forthe treatment of gynecologic disorders, infertility and to affectandrogen production to cause male castration.

DETAILED DESCRIPTION

As noted above, the invention relates to compounds of Formula I:

-   -   and pharmaceutically acceptable solvates thereof, wherein:    -   R¹ is H or F;    -   R^(1′) is H;    -   R² is H, F or Cl;    -   R^(2′) is H or F;    -   R³ is F or Cl;    -   R⁴ is methyl or trifluoromethyl;    -   X¹ is S and X² is N or X¹ is CH and X² is O;    -   represents a single or a double bound depending on X¹ and X²;    -   stands for the (R)-enantiomer or for the racemate of compound of        Formula I.

In an embodiment of the invention, compound of Formula I is the(R)-enantiomer. In another embodiment, compound of Formula I is theracemate.

In one embodiment, preferred compounds of Formula I are those of FormulaI′:

-   -   and pharmaceutically acceptable solvates thereof, wherein R¹,        R^(1′), R², R^(2′), R³, R⁴, X¹ and X² are as defined in Formula        I and        represents a single or a double bound depending on X¹ and X².

In one embodiment, preferred compounds of Formula I are those of FormulaI″:

-   -   and pharmaceutically acceptable solvates thereof, wherein R¹,        R^(1′), R², R^(2′), R³, R⁴, X¹ and X² are as defined in Formula        I and        represents a single or a double bound depending on X¹ and X².

In one embodiment, preferred compounds of Formula I are those of FormulaIa:

-   -   and pharmaceutically acceptable solvates thereof, wherein:    -   R¹ is H or F;    -   R^(1′) is H;    -   R² is H, F or Cl;    -   R^(2′) is H or F;    -   R³ is F or Cl;    -   R⁴ is methyl or trifluoromethyl;    -   stands for the (R)-enantiomer or for the racemate of compound of        Formula Ia.

In one embodiment, preferred compounds of Formula Ia are those ofFormula Ia′:

-   -   and pharmaceutically acceptable solvates thereof, wherein R¹,        R^(1′), R², R^(2′), R³ and R⁴ are as defined in Formula Ia.

In one embodiment, preferred compounds of Formula I are those of FormulaIb:

-   -   and pharmaceutically acceptable solvates thereof, wherein:    -   R¹ is H or F;    -   R¹ is H;    -   R² is H, F or Cl;    -   R^(2′) is H or F;    -   R³ is F or Cl;    -   R⁴ is methyl or trifluoromethyl, preferably R⁴ is methyl;    -   stands for the (R)-enantiomer or for the racemate of compound of        Formula Ib.

In one embodiment, preferred compounds of Formula Ib are those ofFormula Ib′:

-   -   and pharmaceutically acceptable solvates thereof, wherein R¹,        R^(1′), R², R^(2′), R³ and R⁴ are as defined in Formula Ib.

Particularly preferred compounds of Formula I of the invention are thoselisted in Table 1 hereafter.

TABLE 1 Cpd n° Structure Chemical name MW 1

(R)-(4-fluorophenyl)(8- methyl-3-(5-methylfuran-2- yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)methanone 340.35 2

(R)-(4-fluorophenyl)(8- methyl-3-(2-methylthiazol-4- yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)methanone 357.41 3

(R)-(4-fluorophenyl)(8- methyl-3-(2- (trifluoromethyl)thiazol-4-yl)-5,6-dihydro- [1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)methanone 411.38 4

(R)-(8-methyl-3-(5- methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)(2,3,4,5-tetrafluorophenyl)methanone 394.32 5

(R)-(3,4-difluorophenyl)(8- methyl-3-(5-methylfuran-2- yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)methanone 358.34 6

(R)-(8-methyl-3-(5- methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)(2,3,4-trifluorophenyl)methanone 376.33 7

(R)-(8-methyl-3-(5- methylfuran-2-yl)-5,6ydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)(3,4,5-trifluorophenyl)methanone 376.33 8

(R)-(3-chloro-4- fluorophenyl)(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihdro- [1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone 374.80 9

(R)-(4-chloro-3- fluorophenyl)(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro- [1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone 374.80 10

(R)-(4-chlorophenyl)(8- methyl-3-(5-methylfuran-2- yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)methanone 356.81 11

(R)-(3,4-dichlorophenyl)(8- methyl-3-(5-methylfuran-2- yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)methanone 391.25 12

(R)-(8-methyl-3-(2- (trifluoromethyl)thiazol-4-yl)- 5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)(2,3,4,5-tetrafluorophenyl)methanone 465.35 13

(R)-(3,4-difluorophenyl)(8- methyl-3-(2- (trifluoromethyl)thiazol-4-yl)-5,6-dihydro- [1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)methanone 429.37 14

(R)-(8-methyl-3-(2- (trifluoromethyl)thiazol-4-yl)- 5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)(2,3,4-trifluorophenyl)methanone 447.36 15

(R)-(8-methyl-3-(2- (trifluoromethyl)thiazol-4-yl)- 5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)(3,4,5-trifluorophenyl)methanone 447.36 16

(R)-(3-chloro-4- fluorophenyl)(8-methyl-3-(2-(trifluoromethyl)thiazol-4-yl)- 5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)methanone 445.82 17

(R)-(4-chloro-3- fluorophenyl)(8-methyl-3-(2-(trifluoromethyl)thiazol-4-yl)- 5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)methanone 445.82 18

(R)-(4-chlorophenyl)(8- methyl-3-(2- (trifluoromethyl)thiazol-4-yl)-5,6-dihydro- [1,2,4]triazolo[4,3-a]pyrazin- 7(8H)-yl)methanone 427.83and pharmaceutically acceptable solvate thereof.

In Table 1, the term “Cpd” means compound.

The compounds of Table 1 were named using ChemBioDraw® Ultra version12.0 (PerkinElmer).

The compounds of Formula I can be prepared by different ways withreactions known to a person skilled in the art.

The invention further relates to a process of manufacturing of compoundsof Formula I:

-   -   and pharmaceutically acceptable solvates thereof, wherein:    -   R¹ is H or F;    -   R^(1′) is H;    -   R² is H, F or Cl;    -   R^(2′) is H or F;    -   R³ is F or Cl;    -   R⁴ is methyl or trifluoromethyl;    -   X¹ is S and X² is N or X¹ is CH and X² is O;    -   represents a single or a double bound depending on X¹ and X²;    -   stands for the (R)-enantiomer or for the racemate of compound of        Formula I;        characterized in that it comprises the following steps:    -   a) reacting a compound of Formula (i)

-   -   -   wherein:        -   PG represents a suitable protecting group such as for            example DMB, PMB, Boc, preferably PG is DMB;        -   stands for the (R)-enantiomer or for the racemate;

    -   with a compound of Formula (ii)

-   -   -   wherein:        -   R⁴ is as defined above;        -   X¹ and X² are as defined above;        -   represents a single or a double bound depending on X¹ and            X²;

    -   so as to obtain a compound of Formula (iii)

-   -   -   wherein PG, R⁴, X¹ and X² are as defined above,            stands for the (R)-enantiomer or for the racemate and            represents a single or a double bound depending on X¹ and            X²;

    -   b) deprotecting compound of Formula (iii) with a suitable        deprotection agent to afford compound of Formula (iv)

-   -   -   wherein R⁴, X¹ and X² are as defined above,            stands for the (R)-enantiomer or for the racemate and            represents a single or a double bound depending on X¹ and            X²;

    -   c) N-acylating compound of Formula (iv) with a compound of        Formula (v)

-   -   -   wherein R¹, R^(1′), R², R^(2′) and R³ are as defined above;

    -   to afford compound of Formula I as described above.

In a preferred embodiment, the protecting group PG used in the processof the invention is DMB.

Reaction schemes as described in the example section are illustrativeonly and should not be construed as limiting the invention in any way.According to one embodiment, compounds of Formula I can be preparedusing the chiral synthesis of the invention detailed in the examplesbelow.

The invention is further directed to the use of the compounds of theinvention or pharmaceutically acceptable solvates thereof as antagoniststo the NK-3 receptor.

Accordingly, in a particularly preferred embodiment, the inventionrelates to the use of compounds of Formula I and subformulae inparticular those of Table 1 above, or pharmaceutically acceptablesolvates thereof, as NK-3 receptor antagonists.

Accordingly, in another aspect, the invention relates to the use ofthese compounds or solvates thereof for the synthesis of pharmaceuticalactive ingredients, such as selective NK-3 receptor antagonists.

Uses

The compounds of the invention are therefore useful as medicaments, inparticular in the prevention and/or treatment of depression, anxiety,psychosis, schizophrenia, psychotic disorders, bipolar disorders,cognitive disorders, Parkinson's disease, Alzheimer's disease, attentiondeficit hyperactivity disorder (ADHD), pain, convulsion, obesity,inflammatory diseases including irritable bowel syndrome (IBS) andinflammatory bowel disorders, emesis, pre-eclampsia, airway relateddiseases including chronic obstructive pulmonary disease, asthma, airwayhyperresponsiveness, bronchoconstriction and cough, reproductiondisorders, contraception and sex hormone-dependent diseases includingbut not limited to benign prostatic hyperplasia (BPH), prostatichyperplasia, metastatic prostatic carcinoma, testicular cancer, breastcancer, ovarian cancer, androgen dependent acne, male pattern baldness,endometriosis, abnormal puberty, uterine fibrosis, uterine fibroidtumor, hormone-dependent cancers, hyperandrogenism, hirsutism,virilization, polycystic ovary syndrome (PCOS), premenstrual dysphoricdisease (PMDD), HAIR-AN syndrome (hyperandrogenism, insulin resistanceand acanthosisnigricans), ovarian hyperthecosis (HAIR-AN withhyperplasia of luteinized theca cells in ovarian stroma), othermanifestations of high intraovarian androgen concentrations (e.g.follicular maturation arrest, atresia, anovulation, dysmenorrhea,dysfunctional uterine bleeding, infertility), androgen-producing tumor(virilizing ovarian or adrenal tumor), menorrhagia and adenomyosis. Thecompounds of the invention are therefore useful as medicaments, inparticular in the prevention and/or treatment of depression, anxiety,psychosis, schizophrenia, psychotic disorders, bipolar disorders,cognitive disorders, Parkinson's disease, Alzheimer's disease, attentiondeficit hyperactivity disorder (ADHD), pain, convulsion, obesity,inflammatory diseases including irritable bowel syndrome (IBS) andinflammatory bowel disorders, emesis, pre-eclampsia, airway relateddiseases including chronic obstructive pulmonary disease, asthma, airwayhyperresponsiveness, bronchoconstriction and cough, urinaryincontinence, reproduction disorders, contraception and sexhormone-dependent diseases including but not limited to benign prostatichyperplasia (BPH), prostatic hyperplasia, metastatic prostaticcarcinoma, testicular cancer, breast cancer, ovarian cancer, androgendependent acne, male pattern baldness, endometriosis, abnormal puberty,uterine fibrosis, uterine fibroid tumor, uterine leiomyoma,hormone-dependent cancers, hyperandrogenism, hirsutism, virilization,polycystic ovary syndrome (PCOS), premenstrual dysphoric disease (PMDD),HAIR-AN syndrome (hyperandrogenism, insulin resistance and acanthosisnigricans), ovarian hyperthecosis (HAIR-AN with hyperplasia ofluteinized theca cells in ovarian stroma), other manifestations of highintraovarian androgen concentrations (e.g. follicular maturation arrest,atresia, anovulation, dysmenorrhea, dysfunctional uterine bleeding,infertility), androgen-producing tumor (virilizing ovarian or adrenaltumor), menorrhagia and adenomyosis.

The invention also provides for a method for delaying in patient theonset of depression, anxiety, psychosis, schizophrenia, psychoticdisorders, bipolar disorders, cognitive disorders, Parkinson's disease,Alzheimer's disease, attention deficit hyperactivity disorder (ADHD),pain, convulsion, obesity, inflammatory diseases including irritablebowel syndrome (IBS) and inflammatory bowel disorders, emesis,pre-eclampsia, airway related diseases including chronic obstructivepulmonary disease, asthma, airway hyperresponsiveness,bronchoconstriction and cough, reproduction disorders, contraception andsex hormone-dependent diseases including but not limited to benignprostatic hyperplasia (BPH), prostatic hyperplasia, metastatic prostaticcarcinoma, testicular cancer, breast cancer, ovarian cancer, androgendependent acne, male pattern baldness, endometriosis, abnormal puberty,uterine fibrosis, uterine fibroid tumor, hormone-dependent cancers,hyperandrogenism, hirsutism, virilization, polycystic ovary syndrome(PCOS), premenstrual dysphoric disease (PMDD), HAIR-AN syndrome(hyperandrogenism, insulin resistance and acanthosisnigricans), ovarianhyperthecosis (HAIR-AN with hyperplasia of luteinized theca cells inovarian stroma), other manifestations of high intraovarian androgenconcentrations (e.g. follicular maturation arrest, atresia, anovulation,dysmenorrhea, dysfunctional uterine bleeding, infertility),androgen-producing tumor (virilizing ovarian or adrenal tumor),menorrhagia and adenomyosis comprising the administration of apharmaceutically effective amount of a compound of Formula I orpharmaceutically acceptable solvate thereof to a patient in needthereof. The invention also provides for a method for delaying inpatient the onset of depression, anxiety, psychosis, schizophrenia,psychotic disorders, bipolar disorders, cognitive disorders, Parkinson'sdisease, Alzheimer's disease, attention deficit hyperactivity disorder(ADHD), pain, convulsion, obesity, inflammatory diseases includingirritable bowel syndrome (IBS) and inflammatory bowel disorders, emesis,pre-eclampsia, airway related diseases including chronic obstructivepulmonary disease, asthma, airway hyperresponsiveness,bronchoconstriction and cough, urinary incontinence, reproductiondisorders, contraception and sex hormone-dependent diseases includingbut not limited to benign prostatic hyperplasia (BPH), prostatichyperplasia, metastatic prostatic carcinoma, testicular cancer, breastcancer, ovarian cancer, androgen dependent acne, male pattern baldness,endometriosis, abnormal puberty, uterine fibrosis, uterine fibroidtumor, uterine leiomyoma, hormone-dependent cancers, hyperandrogenism,hirsutism, virilization, polycystic ovary syndrome (PCOS), premenstrualdysphoric disease (PMDD), HAIR-AN syndrome (hyperandrogenism, insulinresistance and acanthosis nigricans), ovarian hyperthecosis (HAIR-ANwith hyperplasia of luteinized theca cells in ovarian stroma), othermanifestations of high intraovarian androgen concentrations (e.g.follicular maturation arrest, atresia, anovulation, dysmenorrhea,dysfunctional uterine bleeding, infertility), androgen-producing tumor(virilizing ovarian or adrenal tumor), menorrhagia and adenomyosiscomprising the administration of a pharmaceutically effective amount ofa compound of Formula I or pharmaceutically acceptable solvate thereofto a patient in need thereof.

Preferably, the patient is a warm-blooded animal, more preferably ahuman.

The compounds of the invention are especially useful in the treatmentand/or prevention of sex hormone-dependent diseases including but notlimited to benign prostatic hyperplasia (BPH), prostatic hyperplasia,metastatic prostatic carcinoma, testicular cancer, breast cancer,ovarian cancer, androgen dependent acne, male pattern baldness,endometriosis, abnormal puberty, uterine fibrosis, uterine fibroidtumor, hormone-dependent cancers, hyperandrogenism, hirsutism,virilization, polycystic ovary syndrome (PCOS), premenstrual dysphoricdisease (PMDD), HAIR-AN syndrome (hyperandrogenism, insulin resistanceand acanthosisnigricans), ovarian hyperthecosis (HAIR-AN withhyperplasia of luteinized theca cells in ovarian stroma), othermanifestations of high intraovarian androgen concentrations (e.g.follicular maturation arrest, atresia, anovulation, dysmenorrhea,dysfunctional uterine bleeding, infertility), androgen-producing tumor(virilizing ovarian or adrenal tumor), menorrhagia and adenomyosiscomprising the administration of a therapeutically effective amount of acompound or pharmaceutically acceptable solvate of Formula I, to apatient in need thereof. The compounds of the invention are especiallyuseful in the treatment and/or prevention of sex hormone-dependentdiseases including but not limited to benign prostatic hyperplasia(BPH), prostatic hyperplasia, metastatic prostatic carcinoma, testicularcancer, breast cancer, ovarian cancer, androgen dependent acne, malepattern baldness, endometriosis, abnormal puberty, uterine fibrosis,uterine fibroid tumor, uterine leiomyoma, hormone-dependent cancers,hyperandrogenism, hirsutism, virilization, polycystic ovary syndrome(PCOS), premenstrual dysphoric disease (PMDD), HAIR-AN syndrome(hyperandrogenism, insulin resistance and acanthosis nigricans), ovarianhyperthecosis (HAIR-AN with hyperplasia of luteinized theca cells inovarian stroma), other manifestations of high intraovarian androgenconcentrations (e.g. follicular maturation arrest, atresia, anovulation,dysmenorrhea, dysfunctional uterine bleeding, infertility),androgen-producing tumor (virilizing ovarian or adrenal tumor),menorrhagia and adenomyosis.

In a specific embodiment, the compounds of the invention are especiallyuseful in the treatment and/or prevention of benign prostatichyperplasia (BPH), endometriosis, uterine fibrosis, uterine fibroidtumor, polycystic ovary syndrome (PCOS), premenstrual dysphoric disease(PMDD), HAIR-AN syndrome (hyperandrogenism, insulin resistance andacanthosis nigricans), ovarian hyperthecosis (HAIR-AN with hyperplasiaof luteinized theca cells in ovarian stroma), other manifestations ofhigh intraovarian androgen concentrations (e.g. follicular maturationarrest, atresia, anovulation, dysmenorrhea, dysfunctional uterinebleeding, infertility), androgen-producing tumor (virilizing ovarian oradrenal tumor), menorrhagia and adenomyosis. In a specific embodiment,the compounds of the invention are especially useful in the treatmentand/or prevention of benign prostatic hyperplasia (BPH), endometriosis,uterine fibrosis, uterine fibroid tumor, uterine leiomyoma, polycysticovary syndrome (PCOS), premenstrual dysphoric disease (PMDD), HAIR-ANsyndrome (hyperandrogenism, insulin resistance and acanthosisnigricans), ovarian hyperthecosis (HAIR-AN with hyperplasia ofluteinized theca cells in ovarian stroma), other manifestations of highintraovarian androgen concentrations (e.g. follicular maturation arrest,atresia, anovulation, dysmenorrhea, dysfunctional uterine bleeding,infertility), androgen-producing tumor (virilizing ovarian or adrenaltumor), menorrhagia and adenomyosis.

In a specific embodiment, the compounds of the invention are especiallyuseful in the treatment and/or prevention of endometriosis, uterinefibrosis, uterine fibroid tumor, uterine leiomyoma, polycystic ovarysyndrome (PCOS) and benign prostatic hyperplasia (BPH).

In a specific embodiment, the compounds of the invention are especiallyuseful in the treatment and/or prevention of endometriosis.

In a specific embodiment, the compounds of the invention are especiallyuseful in the treatment and/or prevention of uterine fibrosis.

In a specific embodiment, the compounds of the invention are especiallyuseful in the treatment and/or prevention of uterine fibroid tumor.

In a specific embodiment, the compounds of the invention are especiallyuseful in the treatment and/or prevention of uterine leiomyoma.

In a specific embodiment, the compounds of the invention are especiallyuseful in the treatment and/or prevention of polycystic ovary syndrome(PCOS).

In a specific embodiment, the compounds of the invention are especiallyuseful in the treatment and/or prevention of benign prostatichyperplasia (BPH).

In a specific embodiment, the compounds of the invention are especiallyuseful in the treatment and/or prevention of hot flashes also known ashot flushes.

In a specific embodiment, the compounds of the invention are especiallyuseful in the treatment and/or prevention of peri-menopausal conditions(i.e. ‘hot flashes’), in vitro fertilization (‘IVF’), malecontraceptive, female contraceptive, castration of sex offenders.

The compounds of the invention are also useful in the treatment ofgynecological disorders and infertility. In particular, the inventionprovides methods to lower and/or suppress the LH-surge in assistedconception.

The compounds of the invention are also useful to cause male castrationand to inhibit the sex drive in men. This is of particular interest inthe treatment of male sexual offenders.

The invention further provides the use of a compound of Formula I or apharmaceutically acceptable solvate thereof for the manufacture of amedicament for treating and/or preventing depression, anxiety,psychosis, schizophrenia, psychotic disorders, bipolar disorders,cognitive disorders, Parkinson's disease, Alzheimer's disease, attentiondeficit hyperactivity disorder (ADHD), pain, convulsion, obesity,inflammatory diseases including irritable bowel syndrome (IBS) andinflammatory bowel disorders, emesis, pre-eclampsia, airway relateddiseases including chronic obstructive pulmonary disease, asthma, airwayhyperresponsiveness, bronchoconstriction and cough, reproductiondisorders, contraception and sex hormone-dependent diseases includingbut not limited to benign prostatic hyperplasia (BPH), prostatichyperplasia, metastatic prostatic carcinoma, testicular cancer, breastcancer, ovarian cancer, androgen dependent acne, male pattern baldness,endometriosis, abnormal puberty, uterine fibrosis, uterine fibroidtumor, hormone-dependent cancers, hyperandrogenism, hirsutism,virilization, polycystic ovary syndrome (PCOS), premenstrual dysphoricdisease (PMDD), HAIR-AN syndrome (hyperandrogenism, insulin resistanceand acanthosisnigricans), ovarian hyperthecosis (HAIR-AN withhyperplasia of luteinized theca cells in ovarian stroma), othermanifestations of high intraovarian androgen concentrations (e.g.follicular maturation arrest, atresia, anovulation, dysmenorrhea,dysfunctional uterine bleeding, infertility), androgen-producing tumor(virilizing ovarian or adrenal tumor), menorrhagia and adenomyosis in apatient. The invention further provides the use of a compound of FormulaI or a pharmaceutically acceptable solvate thereof for the manufactureof a medicament for treating and/or preventing depression, anxiety,psychosis, schizophrenia, psychotic disorders, bipolar disorders,cognitive disorders, Parkinson's disease, Alzheimer's disease, attentiondeficit hyperactivity disorder (ADHD), pain, convulsion, obesity,inflammatory diseases including irritable bowel syndrome (IBS) andinflammatory bowel disorders, emesis, pre-eclampsia, airway relateddiseases including chronic obstructive pulmonary disease, asthma, airwayhyperresponsiveness, bronchoconstriction and cough, urinaryincontinence, reproduction disorders, contraception and sexhormone-dependent diseases including but not limited to benign prostatichyperplasia (BPH), prostatic hyperplasia, metastatic prostaticcarcinoma, testicular cancer, breast cancer, ovarian cancer, androgendependent acne, male pattern baldness, endometriosis, abnormal puberty,uterine fibrosis, uterine fibroid tumor, uterine leiomyoma,hormone-dependent cancers, hyperandrogenism, hirsutism, virilization,polycystic ovary syndrome (PCOS), premenstrual dysphoric disease (PMDD),HAIR-AN syndrome (hyperandrogenism, insulin resistance and acanthosisnigricans), ovarian hyperthecosis (HAIR-AN with hyperplasia ofluteinized theca cells in ovarian stroma), other manifestations of highintraovarian androgen concentrations (e.g. follicular maturation arrest,atresia, anovulation, dysmenorrhea, dysfunctional uterine bleeding,infertility), androgen-producing tumor (virilizing ovarian or adrenaltumor), menorrhagia and adenomyosis in a patient.

Preferably, the patient is a warm-blooded animal, more preferably ahuman.

The invention especially provides the use of a compound of Formula I ora pharmaceutically acceptable solvate thereof for the manufacture of amedicament to treat and/or prevent sex hormone-dependent diseasesincluding but not limited to benign prostatic hyperplasia (BPH),prostatic hyperplasia, metastatic prostatic carcinoma, testicularcancer, breast cancer, ovarian cancer, androgen dependent acne, malepattern baldness, endometriosis, abnormal puberty, uterine fibrosis,uterine fibroid tumor, hormone-dependent cancers, hyperandrogenism,hirsutism, virilization, polycystic ovary syndrome (PCOS), premenstrualdysphoric disease (PMDD), HAIR-AN syndrome (hyperandrogenism, insulinresistance and acanthosisnigricans), ovarian hyperthecosis (HAIR-AN withhyperplasia of luteinized theca cells in ovarian stroma), othermanifestations of high intraovarian androgen concentrations (e.g.follicular maturation arrest, atresia, anovulation, dysmenorrhea,dysfunctional uterine bleeding, infertility), androgen-producing tumor(virilizing ovarian or adrenal tumor), menorrhagia and adenomyosiscomprising the administration of a therapeutically effective amount of acompound or pharmaceutically acceptable solvate of Formula I, to apatient in need thereof. The invention especially provides the use of acompound of Formula I or a pharmaceutically acceptable solvate thereoffor the manufacture of a medicament to treat and/or prevent sexhormone-dependent diseases including but not limited to benign prostatichyperplasia (BPH), prostatic hyperplasia, metastatic prostaticcarcinoma, testicular cancer, breast cancer, ovarian cancer, androgendependent acne, male pattern baldness, endometriosis, abnormal puberty,uterine fibrosis, uterine fibroid tumor, uterine leiomyoma,hormone-dependent cancers, hyperandrogenism, hirsutism, virilization,polycystic ovary syndrome (PCOS), premenstrual dysphoric disease (PMDD),HAIR-AN syndrome (hyperandrogenism, insulin resistance and acanthosisnigricans), ovarian hyperthecosis (HAIR-AN with hyperplasia ofluteinized theca cells in ovarian stroma), other manifestations of highintraovarian androgen concentrations (e.g. follicular maturation arrest,atresia, anovulation, dysmenorrhea, dysfunctional uterine bleeding,infertility), androgen-producing tumor (virilizing ovarian or adrenaltumor), menorrhagia and adenomyosis.

In a specific embodiment, compounds of Formula I or a pharmaceuticallyacceptable solvate thereof may be used for the manufacture of amedicament to treat and/or prevent endometriosis, uterine fibrosis,uterine fibroid tumor, uterine leiomyoma, polycystic ovary syndrome(PCOS) and benign prostatic hyperplasia (BPH).

In a specific embodiment, compounds of Formula I or a pharmaceuticallyacceptable solvate thereof may be used for the manufacture of amedicament to treat and/or prevent endometriosis.

In a specific embodiment, compounds of Formula I or a pharmaceuticallyacceptable solvate thereof may be used for the manufacture of amedicament to treat and/or prevent uterine fibrosis.

In a specific embodiment, compounds of Formula I or a pharmaceuticallyacceptable solvate thereof may be used for the manufacture of amedicament to treat and/or prevent uterine fibroid tumor.

In a specific embodiment, compounds of Formula I or a pharmaceuticallyacceptable solvate thereof may be used for the manufacture of amedicament to treat and/or prevent uterine leiomyoma.

In a specific embodiment, compounds of Formula I or a pharmaceuticallyacceptable solvate thereof may be used for the manufacture of amedicament to treat and/or prevent polycystic ovary syndrome (PCOS).

In a specific embodiment, compounds of Formula I or a pharmaceuticallyacceptable solvate thereof may be used for the manufacture of amedicament to treat and/or prevent benign prostatic hyperplasia (BPH).

In a specific embodiment, compounds of Formula I or a pharmaceuticallyacceptable solvate thereof may be used for the manufacture of amedicament to treat and/or prevent hot flashes also knows as hotflushes.

The invention further provides the use of a compound of Formula I or apharmaceutically acceptable solvate thereof for the manufacture of amedicament to lower and/or suppress the LH-surge in assisted conceptionin a patient. Preferably the patient is a warm-blooded animal, morepreferably a woman.

The invention further provides the use of a compound of Formula I or apharmaceutically acceptable solvate thereof for the manufacture of amedicament to cause male castration and to inhibit the sex drive in men.This is of particular interest in the treatment of male sexualoffenders.

The invention further provides the use of a compound of Formula I or apharmaceutically acceptable solvate thereof for the manufacture of amedicament to treat and/or prevent sex hormone-dependent diseasesincluding but not limited to benign prostatic hyperplasia (BPH),prostatic hyperplasia, metastatic prostatic carcinoma, testicularcancer, breast cancer, ovarian cancer, androgen dependent acne, malepattern baldness, endometriosis, abnormal puberty, uterine fibrosis,uterine fibroid tumor, hormone-dependent cancers, hyperandrogenism,hirsutism, virilization, polycystic ovary syndrome (PCOS), premenstrualdysphoric disease (PMDD), HAIR-AN syndrome (hyperandrogenism, insulinresistance and acanthosisnigricans), ovarian hyperthecosis (HAIR-AN withhyperplasia of luteinized theca cells in ovarian stroma), othermanifestations of high intraovarian androgen concentrations (e.g.follicular maturation arrest, atresia, anovulation, dysmenorrhea,dysfunctional uterine bleeding, infertility), androgen-producing tumor(virilizing ovarian or adrenal tumor), menorrhagia and adenomyosiscomprising the administration of a therapeutically effective amount of acompound or pharmaceutically acceptable solvate of Formula I, to apatient in need thereof.

According to a further feature of the present invention there isprovided a method for modulating NK-3 receptor activity, in a patient,preferably a warm blooded animal, and even more preferably a human, inneed of such treatment, which comprises administering to said patient aneffective amount of compound of the present invention, or apharmaceutically acceptable solvate thereof.

According to one embodiment, the compounds of the invention, theirpharmaceutical acceptable solvates may be administered as part of acombination therapy. Thus, are included within the scope of the presentinvention embodiments comprising coadministration of, and compositionsand medicaments which contain, in addition to a compound of the presentinvention, a pharmaceutically acceptable solvate thereof as activeingredient, additional therapeutic agents and/or active ingredients.Such multiple drug regimens, often referred to as “combination therapy”,may be used in the treatment and/or prevention of any of the diseases orconditions mediated by or associated with NK-3 receptor modulation. Theuse of such combinations of therapeutic agents is especially pertinentwith respect to the treatment of the above-mentioned disorders within apatient in need of treatment or one at risk of becoming such a patient.

In addition to the requirement of therapeutic efficacy, which maynecessitate the use of active agents in addition to the NK-3 receptormodulator compounds of Formula I or pharmaceutical acceptable solvatesthereof, there may be additional rationales which compel or highlyrecommend the use of combinations of drugs involving active ingredientswhich represent adjunct therapy, i.e., which complement and supplementthe function performed by the NK-3 receptor modulator compounds of thepresent invention. Suitable supplementary therapeutic agents used forthe purpose of auxiliary treatment include drugs which, instead ofdirectly treating or preventing a disease or condition mediated by orassociated with NK-3 receptor modulation, treat diseases or conditionswhich directly result from or indirectly accompany the basic orunderlying NK-3 receptor modulated disease or condition.

According to a further feature of the present invention, the compound ofFormula I, a pharmaceutically acceptable solvate thereof may be used incombination therapy with antipsychotic drugs (APD), to improve theefficacy and to minimize secondary effects associated to APD includingbut not limited to Dopamine 2/3 and 5-HT2 receptors antagonists. Moreparticular the compound of Formula I, a pharmaceutically acceptablesolvate thereof may be used as an adjunct therapy in combination with anatypical antipsychotic drug, including but not limited to risperidone,clozapine, olanzapine, where the NK-3 receptor modulator may serve arole as dose-limiting for the atypical antipsychotic and therefore sparethe patient from some of the side effect of those atypical antipsychoticdrugs.

Thus, the methods of treatment and pharmaceutical compositions of thepresent invention may employ the compounds of Formula I orpharmaceutical acceptable solvates thereof in the form of monotherapy,but said methods and compositions may also be used in the form ofmultiple therapy in which one or more compounds of Formula I or theirpharmaceutically acceptable solvates are coadministered in combinationwith one or more other therapeutic agents.

In the above-described embodiment combinations of the present invention,the compound of Formula I, a pharmaceutically acceptable solvate thereofand other therapeutic active agents may be administered in terms ofdosage forms either separately or in conjunction with each other, and interms of their time of administration, either serially orsimultaneously. Thus, the administration of one component agent may beprior to, concurrent with, or subsequent to the administration of theother component agent(s).

The invention also provides pharmaceutical compositions comprising acompound of Formula I or a pharmaceutically acceptable solvate thereofand at least one pharmaceutically acceptable carrier, diluent, excipientand/or adjuvant. As indicated above, the invention also coverspharmaceutical compositions which contain, in addition to a compound ofthe present invention, a pharmaceutically acceptable solvate thereof asactive ingredient, additional therapeutic agents and/or activeingredients.

Another object of this invention is a medicament comprising at least onecompound of the invention, or a pharmaceutically acceptable solvatethereof, as active ingredient.

According to a further feature of the present invention there isprovided the use of a compound of Formula I or a pharmaceuticallyacceptable solvate thereof for the manufacture of a medicament formodulating NK-3 receptor activity in a patient, in need of suchtreatment, which comprises administering to said patient an effectiveamount of compound of the present invention, or a pharmaceuticallyacceptable solvate thereof.

Preferably, the patient is a warm-blooded animal, more preferably ahuman.

As set forth above, the compounds of the invention, theirpharmaceutically acceptable solvates may be used in monotherapy or incombination therapy. Thus, according to one embodiment, the inventionprovides the use of a compound of the invention for the manufacture of amedicament for at least one of the purposes described above, whereinsaid medicament is administered to a patient in need thereof, preferablya warm-blooded animal, and even more preferably a human, in combinationwith at least one additional therapeutic agent and/or active ingredient.The benefits and advantages of such a multiple drug regimen, possibleadministration regimens as well as suitable additional therapeuticagents and/or active ingredients are those described above.

Generally, for pharmaceutical use, the compounds of the invention may beformulated as a pharmaceutical preparation comprising at least onecompound of the invention and at least one pharmaceutically acceptablecarrier, diluent, excipient and/or adjuvant, and optionally one or morefurther pharmaceutically active compounds.

By means of non-limiting examples, such a formulation may be in a formsuitable for oral administration, for parenteral administration (such asby intravenous, intramuscular or subcutaneous injection or intravenousinfusion), for topical administration (including ocular), foradministration by inhalation, by a skin patch, by an implant, by asuppository, etc. Such suitable administration forms—which may be solid,semi-solid or liquid, depending on the manner of administration—as wellas methods and carriers, diluents and excipients for use in thepreparation thereof, will be clear to the skilled person; reference ismade to the latest edition of Remington's Pharmaceutical Sciences.

Some preferred, but non-limiting examples of such preparations includetablets, pills, powders, lozenges, sachets, cachets, elixirs,suspensions, emulsions, solutions, syrups, aerosols, ointments, cremes,lotions, soft and hard gelatin capsules, suppositories, drops, sterileinjectable solutions and sterile packaged powders (which are usuallyreconstituted prior to use) for administration as a bolus and/or forcontinuous administration, which may be formulated with carriers,excipients, and diluents that are suitable per se for such formulations,such as lactose, dextrose, sucrose, sorbitol, mannitol, starches, gumacacia, calcium phosphate, alginates, tragacanth, gelatin, calciumsilicate, microcrystalline cellulose, polyvinylpyrrolidone, polyethyleneglycol, cellulose, (sterile) water, methylcellulose, methyl- andpropylhydroxybenzoates, talc, magnesium stearate, edible oils, vegetableoils and mineral oils or suitable mixtures thereof. The formulations canoptionally contain other substances that are commonly used inpharmaceutical formulations, such as lubricating agents, wetting agents,emulsifying and suspending agents, dispersing agents, desintegrants,bulking agents, fillers, preserving agents, sweetening agents, flavoringagents, flow regulators, release agents, etc. The compositions may alsobe formulated so as to provide rapid, sustained or delayed release ofthe active compound(s) contained therein.

The pharmaceutical preparations of the invention are preferably in aunit dosage form, and may be suitably packaged, for example in a box,blister, vial, bottle, sachet, ampoule or in any other suitablesingle-dose or multi-dose holder or container (which may be properlylabeled); optionally with one or more leaflets containing productinformation and/or instructions for use. Generally, such unit dosageswill contain between 0.05 and 1000 mg, and usually between 1 and 500 mg,preferably between 2 and 150 mg of at least one compound of theinvention, e.g. about 2, 4, 8, 16, 32, 64 or 128 mg per unit dosage.According to another embodiment, such unit dosages will contain between0.05 and 1000 mg, and usually between 1 and 500 mg, preferably between 2and 400 mg, preferably between 2 and 200 mg of at least one compound ofthe invention per unit dosage.

Usually, depending on the condition to be prevented or treated and theroute of administration, the active compound of the invention willusually be administered between 0.001 and 10 mg per kilogram bodyweight, more often between 0.01 and 4 mg per kilogram body weight,preferably between 0.02 and 1.5 mg per kilogram body weight, for exampleabout 0.02, 0.04, 0.08, 0.16, 0.32, 0.64, or 1.28 mg, per kilogram bodyweight of the patient per day, which may be administered as a singledaily dose, divided over one or more daily doses, or essentiallycontinuously, e.g. using a drip infusion. According to anotherembodiment, the active compound of the invention will usually beadministered between 0.001 and 10 mg per kilogram body weight, moreoften between 0.01 and 7 mg per kilogram body weight, preferably between0.03 and 3.5 mg per kilogram body weight of the patient per day, whichmay be administered as a single daily dose, divided over one or moredaily doses, or essentially continuously, e.g. using a drip infusion.

According to one embodiment, the active compound of the invention willbe administered as a single daily dose, divided over one, two or moredaily doses, or essentially continuously, e.g. using a drip infusion.

Definitions

The definitions and explanations below are for the terms as usedthroughout the entire application, including both the specification andthe claims.

When describing the compounds of the invention, the terms used are to beconstrued in accordance with the following definitions, unless indicatedotherwise.

The ring atoms of(3-substituted)-(8-methyl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazinesof the invention are numbered based on scheme below.

Bonds from an asymmetric carbon in compounds are generally depictedusing a solid line (—), a solid wedge (

), or a dotted wedge (

). The use of either a solid or dotted wedge to depict bonds from anasymmetric carbon atom is meant to indicate that only the stereoisomershown is meant to be included.

The compounds of Formula I and subformulae thereof contain a stereogeniccarbon center at position 8 and thus may exist as (R)- and(S)-enantiomers. In an embodiment of the invention, compounds of FormulaI are not pure (S)-enantiomers relative to the C8 position.

In the compounds of the invention, a dotted wedge (

) carrying a substituent at the C8 position is used to depict the(R)-enantiomer, thus excluding racemic mixtures thereof.

In the compounds of the invention, a dotted line with a star next to theC8 position (

) is used to depict either a dotted wedge (

) to represent the (R)-enantiomer or a solid line (—) to depict theracemic mixture of (R)- and (S)-enantiomer, which is called “racemate”.

For instance,(R)-(4-fluorophenyl)(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone(compound no 1) is depicted as:

The racemic mixture of this compound,(R)-(4-fluorophenyl)(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanoneis depicted as:

The term “solvate” is used herein to describe a compound in thisinvention that contains stoichiometric or sub-stoichiometric amounts ofone or more pharmaceutically acceptable solvent molecule such asethanol. The term “hydrate” refers to when the said solvent is water.

All references to compounds of Formula I include references to solvates,multi-component complexes and liquid crystals thereof.

The compounds of the invention include compounds of Formula I ashereinbefore defined, including all polymorphs and crystal habitsthereof, prodrugs and prodrugs thereof and isotopically-labeledcompounds of Formula I.

The invention also generally covers all pharmaceutically acceptablepredrugs and prodrugs of the compounds of Formula I.

The term “prodrug” as used herein means the pharmacologically acceptablederivatives of compounds of Formula I, such as for example esters, whosein vivo biotransformation product generates the biologically activedrug. Prodrugs are generally characterized by increased bio-availabilityand are readily metabolized into biologically active compounds in vivo.

The term “predrug”, as used herein, means any compound that will bemodified to form a drug species, wherein the modification may take placeeither inside or outside of the body, and either before or after thepredrug reaches the area of the body where administration of the drug isindicated.

The term “patient” refers to a warm-blooded animal, more preferably ahuman, who/which is awaiting the receipt of, or is receiving medicalcare or is/will be the object of a medical procedure.

The term “human” refers to a subject of both genders and at any stage ofdevelopment (i.e. neonate, infant, juvenile, adolescent, adult).

The terms “treat”, “treating” and “treatment, as used herein, are meantto include alleviating, attenuating or abrogating a condition or diseaseand/or its attendant symptoms.

The terms “prevent”, “preventing” and “prevention”, as used herein,refer to a method of delaying or precluding the onset of a condition ordisease and/or its attendant symptoms, barring a patient from acquiringa condition or disease, or reducing a patient's risk of acquiring acondition or disease.

The term “therapeutically effective amount” (or more simply an“effective amount”) as used herein means the amount of active agent oractive ingredient (e.g. NK-3 antagonist) that is sufficient to achievethe desired therapeutic or prophylactic effect in the patient towhich/whom it is administered.

The term “administration”, or a variant thereof (e.g. “administering”),means providing the active agent or active ingredient (e.g. a NK-3antagonist), alone or as part of a pharmaceutically acceptablecomposition, to the patient in whom/which the condition, symptom, ordisease is to be treated or prevented.

By “pharmaceutically acceptable” is meant that the ingredients of apharmaceutical composition are compatible with each other and notdeleterious to the patient thereof.

The term “antagonist” as used herein means a compound that competitivelyor non-competitively binds to a receptor at the same site as an agonist(for example, the endogenous ligand) and has reversible and competitivebinding affinity to a receptor without direct modulation of receptorsignaling, but that nonetheless occupies the binding site of an agonist(for example, the endogenous ligand) to thereby block agonist-mediatedreceptor signaling.

The term “sex hormone-dependent disease” as used herein means a diseasewhich is exacerbated by, or caused by, excessive, inappropriate orunregulated sex hormone production and/or an extraordinary physiologicalresponse to sex hormones. Examples of such diseases in men include butare not limited to benign prostatic hyperplasia (BPH), prostatichyperplasia, metastatic prostatic carcinoma, testicular cancer, androgendependent acne, male pattern baldness and precocious puberty in boys.Examples of such diseases in women include but are not limited toendometriosis, abnormal puberty, uterine fibrosis, uterine fibroidtumor, uterine leiomyoma, hormone-dependent cancers (ovarian cancer,breast cancer), androgen-producing tumor (virilizing ovarian or adrenaltumor), hyperandrogenism, hirsutism, virilization, polycystic ovarysyndrome (PCOS), premenstrual dysphoric disease (PMDD), HAIR-AN syndrome(hyperandrogenism, insulin resistance and acanthosisnigricans), ovarianhyperthecosis (HAIR-AN with hyperplasia of luteinized theca cells inovarian stroma), other manifestations of high intraovarian androgenconcentrations (e.g. follicular maturation arrest, atresia, anovulation,dysmenorrhea, dysfunctional uterine bleeding, infertility), menorrhagiaand adenomyosis (abnormal endometrial growth within the muscle of theuterus).

The term “Psychotic disorders” as used herein means a group of illnessesthat affect the mind. These illnesses alter a patient's ability to thinkclearly, make good judgments, respond emotionally, communicateeffectively, understand reality, and behave appropriately. When symptomsare severe, patient with psychotic disorders have difficulty staying intouch with reality and are often unable to meet the ordinary demands ofdaily life. Psychotic disorders include but are not limited to,schizophrenia, schizophreniform disorder, schizo-affective disorder,delusional disorder, brief psychotic disorder, shared psychoticdisorder, psychotic disorder due to a general medical condition,substance-induced psychotic disorder or psychotic disorders nototherwise specified (Diagnostic and Statistical Manual of MentalDisorders, Ed. 4th, American Psychiatric Association, Washington, D.C.1994).

The term “pharmaceutical vehicle” as used herein means a carrier orinert medium used as solvent or diluent in which the pharmaceuticallyactive agent is formulated and/or administered. Non-limiting examples ofpharmaceutical vehicles include creams, gels, lotions, solutions, andliposomes.

The present invention will be better understood with reference to thefollowing examples. These examples are intended to representative ofspecific embodiments of the invention, and are not intended as limitingthe scope of the invention.

EXAMPLES Chemistry Examples

All reported temperatures are expressed in degrees Celsius (° C.); allreactions were carried out at room temperature (RT) unless otherwisestated.

All reactions were followed by thin layer chromatography (TLC) analysis(TLC plates, silica gel 60 F₂₅₄, Merck) was used to monitor reactions,establish silica-gel flash chromatography conditions. All other TLCdeveloping agents/visualization techniques, experimental set-up orpurification procedures that were used in this invention, when notdescribed in specific details, are assumed to be known to thoseconversant in the art and are described in such standard referencemanuals as: i) Gordon, A. J.; Ford, R. A. “The Chemist's Companion—AHandbook of Practical Data, Techniques, and References”, Wiley: NewYork, 1972; ii) Vogel's Textbook of Practical Organic Chemistry, PearsonPrentice Hall: London, 1989.

HPLC-MS spectra were typically obtained on an Agilent LCMS usingelectrospray ionization (ESI). The Agilent instrument includes anautosampler 1100, a binary pump 1100, an ultraviolet multi-wavelengthdetector 1100 and a 6100 single-quad mass-spectrometer. Thechromatography column used was Sunfire 3.5 μm, C18, 3.0×50 mm indimensions.

Eluent typically used was a mixture of solution A (0.1% TFA in H₂O) andsolution B (0.1% TFA in MeCN).

Gradient was applied at a flow rate of 1.3 mL per minute as follows:gradient A (for analysis of final compounds and intermediates): held theinitial conditions of 5% solution B for 0.2 min, increased linearly to95% solution B in 6 min, held at 95% during 1.75 min, returned toinitial conditions in 0.25 min and maintained for 2.0 min; gradient B(for analysis of crude samples and reactions mixtures): held the initialconditions of 5% solution B for 0.2 min, increased linearly to 95% in2.0 min, held at 95% during 1.75 min, returned to initial conditions in0.25 min and maintained for 2 min.

Determination of chiral purity was made using chiral HPLC that wasperformed on an Agilent 1100 (binary pump and a ultraviolet multiwavelength detector) with manual or automatic (Autosampler 1100)injection capabilities. Column used is CHIRALPAK IA 5 μm, 4.6×250 mm4.6×250 mm in isocratic mode. Choice of eluent was predicated on thespecifics of each separation. Further details concerning the chiral HPLCmethods used are provided below.

Method A: column CHIRALPAK IA 5 μm, 4.6×250 mm, eluent: EtOAc plus 0.1%of DEA, flow rate: 1.0 mL per minute; UV detection at 254 or 280 nm;column at RT, eluent was used as sample solvent.

Method B: column CHIRALPAK IA 5 μm 4.6×250 mm, eluent: hexane/ethanol(80:20 v/v) plus 0.1% of DEA, flow rate: 1.0 mL per minute; UV detectionat 254 or 280 nm, column at RT, eluent was used as sample solvent.

Preparative HPLC purifications were typically carried out on an Agilent1200 instrument (preparative pump 1200 and ultraviolet multi wavelengthdetector 1200) with manual injection. The chromatography column used wasWaters Sunfire 5 μm, C18, 19×100 mm, or XBridge 5 μm, C18, 19×100 mmdepending on the type of eluent system employed, i.e. low pH or high pHconditions.

For high-pH HPLC purifications, eluent typically consisted of a mixtureof solution A (0.04 M ammonium bicarbonate in H₂O plus 0.1% of conc.NH₄OH) and solution B was MeCN. The gradient was adapted depending onthe impurity profile in each sample purified, thereby allowingsufficient separation between the impurities and the desired compound.

In rare cases when high-pH HPLC purification did not provide sufficientpurity, low-pH HPLC was applied. For low-pH HPLC purifications, eluenttypically consisted of a mixture of solution A (0.1% of TFA in H₂O) andsolution B was MeCN. The gradient was adapted depending on the impurityprofile in each sample purified, thereby allowing sufficient separationbetween the impurities and the desired compound. TFA was removed fromevaporated fractions by liquid-liquid extraction.

¹H (300 MHz), ¹³C NMR (75 MHz) and ¹⁹F NMR (282 MHz) spectra wererecorded on a BrukerAvance DRX 300 instrument. Chemical shifts areexpressed in parts per million, (ppm, δ units). Coupling constants areexpressed in Hertz (Hz). Abbreviations for multiplicities observed inNMR spectra are as follows: s (singlet), d (doublet), t (triplet), q(quadruplet), m (multiplet), br (broad).

Solvents, reagents and starting materials were purchased and used asreceived from commercial vendors unless otherwise specified.

The following abbreviations are used:

Boc: tert-butoxycarbonyl,

Cpd: compound,

DCM: Dichloromethane,

DEA: diethylamine,

DMB: 2,4-dimethoxybenzyl,

DMB-CHO: 2,4-dimethoxybenzaldehyde,

ee: Enantiomeric excess,

eq.: Equivalent(s),

EtOAc: Ethylacetate,

EtOH: Ethanol,

g: Gram(s),

h: Hour(s),

L: Liter(s),

MeOH: Methanol,

μL: Microliter(s),

mg: Milligram(s),

mL: Milliliter(s),

mmol: Millimole(s),

min: Minute(s),

P: UV purity at 254 nm or 215 nm determined by HPLC-MS,

PMB: 4-methoxybenzyl,

RT: Room temperature,

tBu: tert-Butyl,

TBME: tert-Butyl Methyl Ether,

TFA: trifluoroacetic acid,

TLC: Thin layer chromatography.

The intermediates and compounds described below were named usingChemBioDraw® Ultra version 12.0 (PerkinElmer).

I. Racemic Synthesis

I.1. General Synthetic Scheme for Racemic Synthesis

Compounds of the invention may be synthesized using the methodologydescribed in Scheme 1, which represents the racemic product synthesis.The racemic products may then be subjected to chiral HPLC for chiralseparation.

The general synthetic scheme comprises the following steps:

Step 1:

DMB-protected ketopiperazine 1.1 was converted to iminoether 1 by usingthe Meerwein reagent (Et30BF4).

Step 2:

Ester 2.2 was subsequently converted to acyl hydrazide 2. Ester 2.2 maybe obtained be esterification of acid 2.1.

Step 3:

Cyclodehydration between the acyl hydrazide 2 and the iminoether 1furnished the protected triazolopiperazine 3.1. Thereafter, 3.1 wassubjected to acidolytic deprotection to obtain 3.

Step 4:

The thus obtained triazolopiperazine intermediate 3 was acylated throughreaction with the appropriate acid chloride 4.1 to obtain the racemictarget structure represented by the general Formula 4. The chiralcompound 4′ was subsequently obtained by purification using preparativechiral HPLC.

I.2. Step 1: Protection and Conversion to Iminoether 1

Method A: Conversion of DMB-Protected Ketopiperazine 1.1 to Iminoether 1

Method A is the procedure used for the synthesis of the iminoetherintermediate 1 with a DMB protecting group and is detailed below:

Synthesis of1-(2,4-dimethoxybenzyl)-5-ethoxy-6-methyl-1,2,3,6-tetrahydropyrazine 1

Oven-dried (115° C.) sodium carbonate (18.6 g, 98 mmol, 2.25 eq.) wasplaced in a 500 mL round-bottom flask. The round-bottom flask wasbackfilled with Ar and then capped with a rubber septum. A solution of4-(2,4-dimethoxybenzyl)-3-methylpiperazin-2-one 1.1 (20.6 g, 78 mmol, 1eq.) in anhydrous DCM (250 mL) was added, followed bytriethyloxoniumtetrafluoroborate (18.6 g, 98 mmol, 1.25 eq.) in oneportion. Thereafter, the reaction mixture was stirred further at RT for1 h whereupon the reaction mixture was diluted with water (250 mL). Theaqueous layer was extracted with DCM (3×150 mL). The organic layers werecombined, dried over MgSO₄, filtered and concentrated under reducedpressure. The crude compound was then purified on silica gel (EtOAc) toafford the desired product 1 as orange oil. Yield: 13.2 g, 58%. LCMS:P=93%, retention time=1.8 min, (M+H+H₂O)⁺: 311; ¹H-NMR (CDCl₃): δ 7.23(d, J=8.8 Hz, 1H), 6.48 (d, J=8.8 Hz, 1H), 6.44 (s, 1H), 4.02 (m, 2H),3.92 (s, 3H), 3.91 (s, 3H), 3.86 (d, J_(AB)=14.0 Hz, 1H), 3.46 (d,J_(AB)=14.0 Hz, 1H), 3.44 (m, 2H), 3.10 (m, 1H), 2.79 (m, 1H), 2.32 (m,1H), 1.35 (d, J=6.8 Hz, 3H), 1.24 (t, J=6.0 Hz, 3H).

I.3. Step 2: Formation of Acyl Hydrazide 2

Method B: Acyl Hydrazide 2

Method B is the procedure used for the synthesis of the acyl hydrazides2 and is detailed below:

In a round-bottom flask equipped with a condenser, ester 2.2 (1 eq.) isdissolved in anhydrous EtOH and treated with hydrazine hydrate (1.2 to20 eq., preferably 1.5 to 10 eq.) using a temperature range from RT toreflux. After allowing the reaction mixture to come to RT, the solutionis concentrated under reduced pressure. Co-evaporations using a mixtureof commercial anhydrous DCM:MeOH (1:1) may be performed to removeresidual water. The residue is then recrystallized and/or precipitatedor purified on a pad of silica to afford 2.

I.4. Step 3: Cyclodehydration Leading to Triazolopiperazine 3

Method C: Cyclodehydration and Acydolysis

Method C is the procedure used for the synthesis of thetriazolopiperazine 3 and is detailed below:

Step 1:

In a round-bottom flask equipped with a condenser, imino-ether 1(1 eq.)is dissolved in anhydrous MeOH, to which is added 2 (1 eq.) in oneportion. The resulting solution is stirred at reflux overnight.Thereafter, the reaction mixture is brought to RT and the volatiles areremoved under reduced pressure. The crude compound is then purifiedusing silica gel chromatography to afford the desired product 3.1.

Step 2:

In a round-bottom flask containing DCM is added 3.1 (1 eq.). Then, TFA(5 to 75 eq.), is added to the reaction mixture at RT. After 30 minstirring, the mixture is concentrated. Then DCM is added to the residuethus obtained, and washed with saturated NaHCO₃. The aqueous layer isextracted twice with DCM, the organic layers are washed with brine,dried over MgSO₄, filtered and concentrated under reduced pressure toobtain crude 3. The crude 3 may be directly used in the next stepwithout further purification.

I.5. Step 4: Acylation Leading to Final Products

Method D: Acylation and Chiral HPLC Purification

Method D is the procedure used for the synthesis of the racemic product4 and its purification to obtain (R)-enantiomer 4′ compounds of generalFormula I. Method D is detailed below:

To a solution of crude 3 (1 eq.) in anhydrous DCM are added, at RT, 4.1(1.17 to 1.3 eq.), followed by N-methylmorpholine (1 eq. to 3.5 eq.)dropwise over 15 sec. The reaction mixture is stirred at RT for 1 to 30minutes and the milky suspension is poured into 1 M HCl solution ordirectly diluted with DCM. The aqueous phase is extracted with DCM. Theorganic phases are combined, optionally washed with 1 M NaOH, water,brine, dried over MgSO₄ and evaporated to dryness. The residue issolubilized in DCM and Et₂O and is slowly added to induce precipitation.The solid was filtered off, washed with Et₂O and dried under vacuum toafford 4. Alternatively, the residue is preliminary purified on silicagel before precipitation or purified on silica gel only.

Compound 4 may be purified by chiral preparative HPLC according to theabovementioned method to yield the corresponding chiral product (R)-4′.Compounds 4 and 4′ are compounds of Formula I of the invention.

II. Chiral Synthesis

II.1. General Synthetic Scheme for Chiral Synthesis

Chiral compounds of the invention may be synthesized using the chiralprocess of the invention described in Scheme 6.

DMB-protected chiral ketopiperazine C was converted to iminoether D byusing the Meerwein reagent (Et₃OBF₄). Condensation reaction between theacyl hydrazide E and iminoether D was conducted under heating conditionsin methanol to provide DMB protected piperazine F that was subsequentlydeprotected with TFA to yield compound of Formula G. Acylation with theappropriate acid chloride H afforded the final (R)-enantiomer typicallyin >90% enantiomeric excess (chiral HPLC).

II.2. Step 1: Conversion to Iminoether D

Method E: Conversion to Iminoether

General Method E is the procedure used for the synthesis of intermediateD.

Synthesis of(R)-1-(2,4-dimethoxybenzyl)-5-ethoxy-6-methyl-1,2,3,6-tetrahydropyrazineD

Oven dried (115° C.) sodium carbonate (2.48 g, 23.40 mmol, 2.25 eq.) wasplaced in a round-bottom flask. The round-bottom flask was backfilledwith Ar and then capped with a rubber septum. A solution of(R)-4-(2,4-dimethoxybenzyl)-3-methylpiperazin-2-one C (2.75 g, 10.40mmol, 1 eq.) in anhydrous DCM (35 mL) was added, followed by freshlyprepared triethyloxoniumtetrafluoroborate (2.48 g, 13.05 mmol, 1.25 eq.)in one portion. Thereafter the reaction mixture was stirred further atRT for 45 min to 1 hour, whereupon the reaction mixture was diluted withsaturated aqueous NaHCO₃ (100 mL). The aqueous layer was extracted withDCM (3×200 mL). The organic layers were combined, dried over MgSO₄,filtered and concentrated under reduced pressure to afford 3.1 g ofyellow oil. The crude compound was then purified on silica gel(EtOAc/MeOH: 99/1) to afford the desired product D as a pale yellow oil.Yield: 1.44 g, 48%. LCMS: P=95%, retention time=1.8 min, (M+H2O+H)⁺:311; chiral HPLC retention time=12.3 min, ee>97%. ¹H-NMR (CDCl₃): δ 7.23(d, J=8.8, 1H), 6.48 (d, J=8.8, 1H), 6.44 (s, 1H), 4.02 (m, 2H), 3.92(s, 6H), 3.86 (d, J_(AB)=14.0, 1H), 3.46 (d, J_(AB)=14.0, 1H), 3.44 (m,2H), 3.10 (m, 1H), 2.79 (m, 1H), 2.32 (m, 1H), 1.35 (d, J=6.8, 3H), 1.24(t, J=6.0, 3H).

The reaction mixture may alternatively be treated with brine. Afterstirring for about 20 min, additional water and DCM were added leadingto phase separation. The organic layers were then dried over MgSO₄,filtered and concentrated under reduced pressure. The crude compound wasthen purified using flash chromatography on silica gel.

II.3. Step 2: Cyclodehydration Leading to F

Method F: Cyclodehydration

General Method F is the general procedure used for the synthesis ofchiral triazolopiperazine intermediates F.

In a round-bottom flask equipped with a condenser, imino-ether D (1 eq.)was dissolved in anhydrous MeOH, to which was added E (1 eq.) in oneportion. The resulting solution was stirred at a temperature rangingfrom 55° C. to 70° C. for a period of time ranging from 6 hours to 34hours. Completion of the reaction was monitored by HPLC analysis. Thereaction mixture was cooled down to RT and the solvent was removed underreduced pressure. The crude compound was then purified by silica gelchromatography to afford the desired product F.

In an embodiment of the invention, the crude compound precipitatesduring cooling of the reaction mixture. In this case, the precipitate isstirred at RT in MeOH for about 5 hours before being filtered, washedwith MeOH and oven dried.

II.4. Step 3: Deprotection Leading to Triazolopiperazine G

Method G: DMB Deprotection—TFA/DCM

Deprotection may be performed using TFA. In this case, F was dissolvedin DCM. TFA (7.6 eq.) was added to the DCM solution of F at RT. Themixture was stirred at RT for 2 h-2 h 30. Completion of the deprotectionwas monitored by HPLC. Water was added, the mixture stirred for 30minutes and filtered. The filter cake was washed with water and DCM. Thefiltrate layers were separated. The pH of the aqueous layer was adjustedto 12-13 by the addition of 4M NaOH. Sodium chloride was then added andthe aqueous solution was extracted with DCM. The DCM extract comprisingG was concentrated and was used in the next step without furtherpurification.

II.5. Step 4: Acylation Leading to Final Products

Method H: Acylation NMM/DCM

General Method H is the general procedure used for the synthesis of(R)-enantiomer of Formula I of the invention.

To a solution of crude G (1 eq.) in anhydrous DCM were added at 0° C. H(1.3 eq.), followed by N-methylmorpholine (2.2 eq.) dropwise over 15sec. The reaction mixture was stirred at RT for 10 minutes and, themilky suspension was poured into 1 M HCl. The aqueous phase wasextracted with DCM. The organic phases were combined, washed with 1 MNaOH, brine, dried over MgSO₄ and evaporated to dryness. The crudecompound was purified by silica gel chromatography to afford the desiredproduct (R)—I.

Measurement of % ee confirmed that no detectable racemization occursduring the acidolytic deprotection and N-acylation steps.

Method I: Acylation—Biphasic Conditions

Alternatively, the reaction may be performed under biphasic conditions.

In this case, saturated sodium hydrogen carbonate solution was added tothe DCM slurry of G (1 eq.) at RT. H (1 eq.) was added and the mixturestirred for a period of time ranging from about 20 minutes to overnightat RT. Completion of the reaction was monitored by HPLC. The layers wereseparated and the DCM phase washed with water. The DCM extracts weredried with magnesium sulfate and filtered, washing the filter cake withDCM. The DCM extracts were then concentrated. TBME was added and theresulting slurry stirred overnight at RT. The solid was collected byfiltration, washed with TBME and pulled dry. The crude compound may bepurified by silica gel chromatography or by crystallisation.

Measurement of % ee confirmed that no detectable racemization occursduring the acidolytic deprotection and N-acylation steps.

III. Chemical Characterization

Compound 1: HPLC-MS: t_(R)=3.2 min, (M+H)⁺=341; Chiral HPLC (Method B):% ee=99.2; ¹H-NMR (CDCl₃): δ7.5 (m, 2H), 7.2 (m, 2H), 6.9 (m, 1H), 6.2(m, 1H), 5.6 (m, 1H), 4.7 (m, 1H), 4.4 (m, 1H), 4.2 (m, 1H), 3.5 (m,1H), 2.4 (s, 3H), 1.7 (d, 3H); ¹⁹F-NMR (CDCl₃): δ−96.4.

Compound 2: HPLC-MS: t_(R)=4.4 min, (M+H)⁺=358; Chiral HPLC (Method A):% ee=97.1; ¹H-NMR (CDCl₃): δ 8.0 (s, 1H), 7.5 (m, 2H), 7.1 (m, 2H), 5.7(m, 1H), 4.9 (dd, 1H), 4.5 (m, 1H), 4.2 (td, 1H), 3.5 (td, 1H), 2.8 (s,3H), 1.7 (d, 3H); ¹⁹F-NMR (CDCl₃): δ−98.0.

Compound 3: HPLC-MS: t_(R)=4.0 min, (M+H)⁺=412; Chiral HPLC (Method B):% ee=97.2; ¹H-NMR (CDCl₃): δ8.4 (s, 1H), 7.5 (m, 2H), 7.2 (m, 2H), 5.8(m, 1H), 4.9 (dd, 1H), 4.6 (m, 1H), 4.3 (td, 1H), 3.5 (td, 1H), 1.7 (d,3H); ¹⁹F-NMR (CDCl₃): δ−58.3, 98.2.

Compound 4: HPLC-MS: t_(R)=3.4 min, (M+H)⁺=359; Chiral HPLC (Method B):% ee=97.2; ¹H-NMR (CDCl₃): δ7.0 (m, 1H), 6.2 (m, 1H), 5.1 (m, 1H), 4.4(m, 1H), 4.1 (m, 1H), 3.8-3.4 (m, 1H), 2.4 (s, 3H), 1.7 (m, 3H); ¹⁹F-NMR(CDCl₃): δ−54.2, −56.3, −67.1, −71.1.

Compound 5: HPLC-MS: t_(R)=3.9 min, (M+H)⁺=359; Chiral HPLC (Method B):% ee=97.1; ¹H-NMR (CDCl₃): δ7.4 (m, 3H), 7.0 (d, 1H), 6.2 (d, 1H), 5.6(m, 1H), 4.6 (m, 1H), 4.4 (dd, 1H), 4.2 (td, 1H), 3.5 (td, 1H), 2.4 (s,3H), 1.7 (d, 3H); ¹⁹F-NMR (CDCl₃): δ−71.7, −74.3.

Compound 6: HPLC-MS: t_(R)=4.1 min, (M+H)⁺=377; Chiral HPLC (Method B):% ee=98.1; ¹H-NMR (CDCl₃): δ7.1 (m, 2H), 7.0 (d, 1H), 6.2 (d, 1H), 6.1(m, 1H), 5.1-5.0 (m, 1H), 4.5 (m, 1H), 4.2 (m, 1H), 3.8-3.7 (m, 1H), 2.4(s, 3H), 1.7 (m, 3H).

Compound 7: HPLC-MS: t_(R)=4.2 min, (M+H)⁺=377; Chiral HPLC (Method B):% ee=98.7; ¹H-NMR (CDCl₃): δ7.1 (m, 2H), 7.0 (d, 1H), 6.2 (d, 1H), 5.6(m, 1H), 4.6 (m, 1H), 4.5 (dd, 1H), 4.2 (td, 1H), 3.5 (td, 1H), 2.4 (s,3H), 1.7 (d, 3H); ¹⁹F-NMR (CDCl₃): δ−75.7.

Compound 8: HPLC-MS: t_(R)=4.2 min, (M+H)⁺=375; Chiral HPLC (Method B):% ee=98.1; ¹H-NMR (CDCl₃): δ7.6 (m, 1H), 7.4 (m, 1H), 7.2 (m, 1H), 7.0(d, 1H), 6.2 (d, 1H), 5.6 (m, 1H), 4.6 (m, 1H), 4.5 (dd, 1H), 4.2 (td,1H), 3.5 (td, 1H), 2.4 (s, 3H), 1.7 (d, 3H); ¹⁹F-NMR (CDCl₃): δ−96.1.

Compound 9: HPLC-MS: t_(R)=4.2 min, (M+H)⁺=375; Chiral HPLC (Method B):% ee=98.1; ¹H-NMR (CDCl₃): δ7.5 (m, 1H), 7.3 (m, 1H), 7.2 (m, 1H), 7.0(d, 1H), 6.2 (d, 1H), 5.6 (m, 1H), 4.6 (m, 1H), 4.4 (dd, 1H), 4.2 (td,1H), 3.5 (td, 1H), 2.4 (s, 3H), 1.7 (d, 3H); ¹⁹F-NMR (CDCl₃): δ−94.2.

Compound 10: HPLC-MS: t_(R)=4.1 min, (M+H)⁺=357; Chiral HPLC (Method B):% ee=98.3; ¹H-NMR (CDCl₃): δ7.4 (m, 4H), 7.0 (d, 1H), 6.2 (d, 1H), 5.6(m, 1H), 4.6 (m, 1H), 4.4 (dd, 1H), 4.2 (td, 1H), 3.4 (td, 1H), 2.4 (s,3H), 1.7 (d, 3H).

Compound 11: HPLC-MS: t_(R)=4.4 min, (M+H)⁺=391; Chiral HPLC (Method B):% ee=97.7; ¹H-NMR (CDCl₃): δ7.6 (m, 2H), 7.2 (m, 1H), 7.0 (d, 1H), 6.2(d, 1H), 5.6 (m, 1H), 4.6 (m, 1H), 4.5 (dd, 1H), 4.2 (td, 1H), 3.5 (td,1H), 2.4 (s, 3H), 1.7 (d, 3H).

Compound 12: HPLC-MS: t_(R)=4.9 min, (M+H)⁺=466; Chiral HPLC (Method B):% ee=96.7; ¹H-NMR (CDCl₃): δ8.4 (s, 1H), 7.1 (m, 1H), 6.1 (m, 1H),5.2-5.1 (m, 1H), 4.9 (dd, 1H), 4.2 (m, 1H), 3.9-3.5 (m, 1H), 1.8 (m,3H); ¹⁹F-NMR (CDCl₃): δ−58.3, −71.1.

Compound 13: HPLC-MS: t_(R)=4.6 min, (M+H)⁺=430; Chiral HPLC (Method B):% ee=96.3; ¹H-NMR (CDCl₃): δ8.4 (s, 1H), 7.3 (m, 3H), 5.7 (m, 1H), 4.9(dd, 1H), 4.5 (m, 1H), 4.3 (td, 1H), 3.6 (td, 1H), 1.8 (d, 3H); ¹⁹F-NMR(CDCl₃): δ−58.3, −71.8, −73.6.

Compound 14: HPLC-MS: t_(R)=4.8 min, (M+H)⁺=448; Chiral HPLC (Method B):% ee=95.2; ¹H-NMR (CDCl₃): δ8.5 (s, 1H), 7.1 (m, 3H), 6.2 (m, 1H),5.2-5.1 (m, 1H), 4.9 (dd, 1H), 4.2 (m, 1H), 3.9-3.4 (m, 1H), 1.8 (m,3H); ¹⁹F-NMR (CDCl₃): δ−58.3, −77.4.

Compound 15: HPLC-MS: t_(R)=4.86 min, (M+H)⁺=448; Chiral HPLC (MethodB): % ee=95.4; ¹H-NMR (CDCl₃): δ8.5 (s, 1H), 7.2 (m, 3H), 6.2 (m, 1H),5.2-5.1 (m, 1H), 4.9 (dd, 1H), 4.2 (m, 1H), 3.9-3.5 (m, 1H), 1.8 (m,3H); ¹⁹F-NMR (CDCl₃): δ−58.3, −77.1.

Compound 16: HPLC-MS: t_(R)=4.8 min, (M+H)⁺=446; Chiral HPLC (Method B):% ee=95.8; ¹H-NMR (CDCl₃): δ8.4 (s, 1H), 7.6 (m, 1H), 7.4 (m, 1H), 7.3(m, 1H), 5.7 (m, 1H), 4.9 (dd, 1H), 4.6 (m, 1H), 4.3 (td, 1H), 3.6 (td,1H), 1.8 (d, 3H); ¹⁹F-NMR (CDCl₃): δ−58.3, −96.0.

Compound 17: HPLC-MS: t_(R)=4.9 min, (M+H)⁺=446; Chiral HPLC (Method B):% ee=95.4; ¹H-NMR (CDCl₃): δ8.5 (s, 1H), 7.5 (m, 1H), 7.3 (m, 1H), 7.2(m, 1H), 5.7 (m, 1H), 4.9 (dd, 1H), 4.5 (m, 1H), 4.3 (td, 1H), 3.6 (td,1H), 1.8 (d, 3H); ¹⁹F-NMR (CDCl₃): δ−58.3, −94.2.

Compound 18: HPLC-MS: t_(R)=4.8 min, (M+H)⁺=428; Chiral HPLC (Method B):% ee=96.4; ¹H-NMR (CDCl₃): δ8.4 (s, 1H), 7.4 (m, 4H), 5.7 (m, 1H), 4.8(dd, 1H), 4.5 (m, 1H), 4.2 (td, 1H), 3.5 (td, 1H), 1.7 (d, 3H); ¹⁹F-NMR(CDCl₃): δ−58.3.

Biology Examples

Functional Assay

Aequorin Assay with Human NK-3 Receptor

Changes in intracellular calcium levels are a recognized indicator of Gprotein-coupled receptor activity. The efficacy of compounds of theinvention to inhibit NKA-mediated NK-3 receptor activation was assessedby an in vitro Aequorin functional assay. Chinese Hamster Ovaryrecombinant cells expressing the human NK-3 receptor and a constructthat encodes the photoproteinapoaequorin were used for this assay. Inthe presence of the cofactor coelenterazine, apoaequorin emits ameasurable luminescence that is proportional to the amount ofintracellular (cytoplasmic) free calcium.

Antagonist Testing

The antagonist activity of compounds of the invention is measuredfollowing pre-incubation (3 minutes) of the compound (at variousconcentrations) with the cells, followed by addition of the referenceagonist (NKA) at a final concentration equivalent to the EC₈₀ (3 nM) andrecording of emitted light (FDSS 6000 Hamamatsu) over the subsequent90-second period. The intensity of the emitted light is integrated usingthe reader software. Compound antagonist activity is measured based onthe concentration-dependent inhibition of the luminescence response tothe addition of Neurokinin A.

Inhibition curves are obtained for compounds of the invention and theconcentrations of compounds which inhibit 50% of reference agonistresponse (IC₅₀) were determined (see results in Table 2 below). The IC₅₀values shown in Table 2 indicate that compounds of the invention arepotent NK-3 antagonist compounds.

Competitive Binding Assays

The affinity of compounds of the invention for the human NK-3 receptorwas determined by measuring the ability of compounds of the invention tocompetitively and reversibly displace a well-characterized NK-3radioligand in a concentration-dependent manner.

³H-SB222200 Binding Competition Assay with Human NK-3 Receptor

The ability of compounds of the invention to inhibit the binding of theNK-3 receptor selective antagonist ³H-SB222200 was assessed by an invitro radioligand binding assay. Membranes were prepared from Chinesehamster ovary recombinant cells stably expressing the human NK-3receptor. The membranes were incubated with 5 nM ³H-SB222200 (ARC) in aHEPES 25 mM/NaCl 0.1M/CaCl₂ 1 mM/MgCl₂ 5 mM/BSA 0.5%/Saponin 10 μg/mlbuffer at pH 7.4 and various concentrations of compounds of theinvention. The amount of ³H-SB222200 bound to the receptor wasdetermined after filtration by the quantification of membrane associatedradioactivity using the TopCount-NXT reader (Packard). Competitioncurves were obtained for compounds of the invention and theconcentration that displaced 50% of bound radioligand (IC₅₀) weredetermined by linear regression analysis and then the apparentinhibition constant (K_(i)) values were calculated by the followingequation: K_(i)=IC₅₀/(1+[L]/K_(d)) where [L] is the concentration offree radioligand and K_(d) is its dissociation constant at the receptor,derived from saturation binding experiments (Cheng and Prusoff, 1973)(see results in Table 2 below).

Table 2 shows biological results obtained using the ³H-SB222200 bindingcompetition assay with compounds of the invention. These resultsindicate that compounds of the invention display potent affinity for thehuman NK-3 receptor.

TABLE 2 Functional assay: Aequorin assay Competitive binding assay withhuman NK-3 receptor with human NK-3 receptor Cpd n° hNK-3 - AEQ(antagonist IC₅₀, nM) hNK-3 (K_(i), nM) 1 60 48 2 160 100 3 20 22 4 7252 5 52 42 6 99 74 7 57 33 8 62 44 9 53 38 10 74 36 11 36 27 12 33 29 1326 20 14 59 40 15 24 13 16 23 14 17 37 22 18 31 21Selectivity Assay

Selectivity of the compounds of the invention was determined over theother human NK receptors, namely NK-1 and NK-2 receptors.

Human NK-1

The affinity of compounds of the invention for the NK-1 receptor wasevaluated in CHO recombinant cells which express the human NK-1receptor. Membrane suspensions were prepared from these cells. Thefollowing radioligand: [³H] substance P (PerkinElmer Cat#NET111520) wasused in this assay. Binding assays were performed in a 50 mM Tris/5 mMMnCl₂/150 mM NaCl/0.1% BSA at pH 7.4. Binding assays consisted of 25 μlof membrane suspension (approximately 5 μg of protein/well in a 96 wellplate), 50 μl of compound or reference ligand (Substance P) atincreasing concentrations (diluted in assay buffer) and 2 nM [³H]substance P. The plate was incubated 60 min at 25° C. in a water bathand then filtered over GF/C filters (Perkin Elmer, 6005174, presoaked in0.5% PEI for 2 h at room temperature) with a Filtration unit (PerkinElmer). The radioactivity retained on the filters was measured by usingthe TopCount-NXT reader (Packard). Competition curves were obtained forcompounds of the invention and the concentrations of compounds whichdisplaced 50% of bound radioligand (IC₅₀) were determined and thenapparent inhibition constant Ki values were calculated by the followingequation: Ki=IC₅₀/(1+[L]/K_(D)) where [L] is the concentration of freeradioligand and K_(D) is its dissociation constant at the receptor,derived from saturation binding experiments (Cheng and Prusoff, 1973).

Human NK-2

The affinity of compounds of the invention for the NK-2 receptor wasevaluated in CHO recombinant cells which express the human NK-2receptor. Membrane suspensions were prepared from these cells. Thefollowing radioligand [¹²⁵I]-Neurokinin A (PerkinElmer Cat#NEX252) wasused in this assay. Binding assays were performed in a 25 mM HEPES/1 mMCaCl₂/5 mM MgCl₂/0.5% BSA/10 μg/ml saponin, at pH 7.4. Binding assaysconsisted of 25 μl of membrane suspension (approximately 3.75 μg ofprotein/well in a 96 well plate), 50 μl of compound or reference ligand(Neurokinin A) at increasing concentrations (diluted in assay buffer)and 0.1 nM [¹²⁵I]-Neurokinin A. The plate was incubated 60 min at 25° C.in a water bath and then filtered over GF/C filters (Perkin Elmer,6005174, presoaked in assay buffer without saponine for 2 h at roomtemperature) with a Filtration unit (Perkin Elmer). The radioactivityretained on the filters was measured by using the TopCount-NXT reader(Packard). Competition curves were obtained for compounds of theinvention and the concentrations of compounds which displaced 50% ofbound radioligand (IC₅₀) were determined and then apparent inhibitionconstant Ki values were calculated by the following equation:Ki=IC₅₀/(1+[L]/K_(D)) where [L] is the concentration of free radioligandand K_(D) is its dissociation constant at the receptor, derived fromsaturation binding experiments (Cheng and Prusoff, 1973).

The compounds of the invention, which were tested in the above NK-1 andNK-2 described assays, demonstrated a low affinity at the human NK-1 andhuman NK-2 receptors: more than 100 fold shift of the K_(i) compared tothe human NK-3 receptor (table 3). Thus, compounds according to theinvention have been shown to be selective over NK-1 and NK-2 receptors.

TABLE 3 Cpd n° hNK-3 (K_(i), nM) hNK-1 (K_(i), nM) hNK-2 (K_(i), nM) 148 >30000 52000 2 100 >30000 >30000 3 22 >30000 6600 4 52 >30000 30000 542 >30000 31000 6 74 >30000 >30000 7 33 27000 21000 8 44 18000 9100 9 3813000 14000 10 36 25000 23000 11 27 6900 4200 12 29 19000 4700 13 2021000 7000 14 40 28000 15000 15 13 24000 3500 16 14 9400 1500 17 2212000 5200 18 21 15000 5900hERGinhibition Assay

The human ether-a-go-go related gene (hERG) encodes the inwardrectifying voltage gated potassium channel in the heart (I_(Kr)) whichis involved in cardiac repolarisation. I_(Kr) current inhibition hasbeen shown to elongate the cardiac action potential, a phenomenonassociated with increased risk of arrhythmia. I_(Kr) current inhibitionaccounts for the vast majority of known cases of drug-inducedQT-prolongation. A number of drugs have been withdrawn from late stageclinical trials due to these cardiotoxic effects, therefore it isimportant to identify inhibitors early in drug discovery.

The hERG inhibition study aims at quantifying the in vitro effects ofcompounds of the invention on the potassium-selective IK_(r) currentgenerated in normoxic conditions in stably transfected HEK 293 cellswith the human ether-a-go-go-related gene (hERG).

Whole-cell currents (acquisition by manual patch-clamp) elicited duringa voltage pulse were recorded in baseline conditions and followingapplication of tested compounds (5 minutes of exposure). Theconcentrations of tested compounds (0.3 μM; 3 μM; 10 μM; 30 μM) reflecta range believed to exceed the concentrations at expected efficacy dosesin preclinical models.

The pulses protocol applied is described as follow: the holdingpotential (every 3 seconds) was stepped from −80 mV to a maximum valueof +40 mV, starting with −40 mV, in eight increments of +10 mV, for aperiod of 1 second. The membrane potential was then returned to −55 mV,after each of these incremented steps, for 1 second and finallyrepolarized to −80 mV for 1 second.

The current density recorded were normalized against the baselineconditions and corrected for solvent effect and time-dependent currentrun-down using experimental design in test compound free conditions.

Inhibition curves were obtained for compounds and the concentrationswhich decreased 50% of the current density determined in the baselineconditions (IC₅₀) were determined. All compounds for which the IC₅₀value is above 10 μM are not considered to be potent inhibitors of thehERG channel whereas compounds with IC₅₀ values below 1 μM areconsidered potent hERG channel inhibitors.

When tested in the hERG inhibition assay, compounds of the inventionwere determined to have IC₅₀ values as shown in Table 4.

Determination of Plasma Protein Binding

The pharmacokinetic and pharmacodynamic properties of chemicals/drugsare largely a function of the reversible binding of chemicals to plasmaor serum proteins. Generally, only the unbound or “free fraction” of adrug is available for diffusion or transport across cell membranes, andfor interaction with a pharmacological/toxicological target.Consequently, the extent of the plasma protein binding (PPB) of acompound influences its action as well as its distribution andelimination.

The determination of plasma protein binding (PPB) of a compound isenabled by equilibrium dialysis, an accepted and standard method forreliable estimation of the non-bound drug fraction in plasma. RED (RapidEquilibrium Dialysis) device insert is made of two side-by-side chambersseparated by an O-ring-sealed vertical cylinder of dialysis membrane(MWCO ˜8,000). Plasma containing drug (at 5 μM or blood concentrationsotherwise corresponding to efficacious doses, if known) is added to onechamber while buffer is added to the second. After 4 hours incubation at37° C. under shaking, an aliquot is removed from each chamber andanalyzed by a LC-MS/MS procedure enables the determination of both freeand bound drug.

The percentages provided in Table 4 represent for the compounds of theinvention the bound drug fraction to the plasma protein. The “freefraction” may be calculated as 100%-% rPPB (i.e. the complementarypercentage of that disclosed in Table 4, corresponding to the drugconcentration that is unbound and therefore available to engagebiological target and elicit pharmacological activity).

TABLE 4 Exposure CardioSafety Cpd n° (% rPPB) (hERG IC₅₀, μM) 1 28 31 217 NA 3 50 70 4 30 NA 5 27 NA 6 37 NA 7 26 NA 8 47 NA 9 68 NA 10 56 NA11 76 NA 12 67 NA 13 51 NA 14 69 NA 15 60 NA 16 82 NA 17 84 NA 18 78 NANA: not availableIn Vivo Assay to Assess Compound Activity in Rat (Oral Dosing)

The effect of compounds of the invention to inhibit luteinizing hormone(LH) secretion is determined by the following biological studies.

Castrated Male Rat Model to Assess the Effect of Compound of Inventionon Circulating Levels of Luteinizing Hormone (LH)

In humans and rodents, castration is well-precedented to permitheightened, persistent GnRH signaling and consequent elevation ofcirculating LH. Thus, a castrated rat model is used to provide a broadindex for measurement of LH inhibition as a marker of test compoundinhibition of the GnRH signaling pathway.

Castrated adult male Sprague-Dawley (SD) rats (150-175 g,) werepurchased from Janvier (St Berthevin, France). All animals were housed 2per cage in a temperature-controlled room (22±2° C.) and 50±5% relativehumidity with a 12 hour/12 hour light/dark cycles (lights off at 6 h 00pm). The animals were allowed 3 weeks of postoperative recovery prior tostudy. Animals were handled on a daily basis. Standard diet and tapwater were provided ad libitum. Animal cage litters were changed once aweek. On the study day, animals were acclimated to the procedure roomfor a period of one hour prior to the initiation of the experiment.

Compounds of the invention were formulated in 0.5% methyl cellulose.

After basal sampling (T0) a single dose of compounds of the invention orvehicle was administrated orally to rats. Blood samples were thencollected at several time points post dosing (45, 90, 150, 300 and 420minutes). Blood samples were obtained via tail vein bleed, drawn intoEDTA-containing tubes and centrifuged immediately. Plasma samples werecollected and stored in a −80° C. freezer until assayed. Serum LH levelswere determined using radioimmunoassay kit from RIAZEN—Rat LH, Zentech(Liege, Belgium). Baseline was defined as the initial basal bloodsample.

When tested in the castrated male rat model described above, compound no1 of the invention significantly suppressed circulating LH levels(statistically significant, p<0.05) at a dose less than or equal to 30mg/kg).

The invention claimed is:
 1. A process of manufacturing a compound ofFormula I:

or a pharmaceutically acceptable solvate thereof, wherein: R¹ is H or F;R^(1′) is H; R² is H, F, or Cl; R^(2′) is H or F; R³ is F or Cl; R⁴ ismethyl or trifluoromethyl; X¹ is S and X² is N, or X¹ is CH and X² is O;

represents a single or a double bond depending on X¹ and X²; and

represents an (R)-enantiomer or a racemate of the compound of Formula I;the process comprising the following steps: (a) reacting a compound ofFormula (i)

wherein PG represents a suitable protecting group;

stands for the (R)-enantiomer or for the racemate; with a compound ofFormula (ii)

wherein: R⁴, X¹, and X² are as defined above, and

represents a single or a double bound depending on X¹ and X²; so as toobtain a compound of Formula (iii)

wherein PG, R⁴, X¹ and X² are as defined above,

stands for the (R)-enantiomer or for the racemate, and

represents a single or a double bound depending on X¹ and X²; (b)deprotecting the compound of Formula (iii) with a suitable deprotectionagent to afford the compound of Formula (iv)

wherein R⁴, X¹ and X² are as defined above,

stands for the (R)-enantiomer or for the racemate, and

represents a single or a double bound depending on X¹ and X²; (c)N-acylating compound of Formula (iv) with a compound of Formula (v)

wherein R¹, R^(1′), R², R^(2′) and R³ are as defined above; to affordthe compound of Formula I as defined above.
 2. The process of claim 1,wherein the compound of Formula I is a compound of Formula I′:

or a pharmaceutically acceptable solvate thereof, wherein R¹ is H or F;R^(1′) is H; R² is H, F, or Cl; R^(2′) is H or F; R³ is F or Cl; R⁴ ismethyl or trifluoromethyl; X¹ is S and X² is N, or X¹ is CH and X² is O;and

represents a single or a double bound depending on X¹ and X².
 3. Theprocess of claim 1, wherein the compound of Formula I is a compound ofFormula I″:

or a pharmaceutically acceptable solvate thereof, wherein R¹ is H or F;R^(1′) is H; R² is H, F, or Cl; R^(2′) is H or F; R³ is F or Cl; R⁴ ismethyl or trifluoromethyl; X¹ is S and X² is N, or X¹ is CH and X² is O;and

represents a single or a double bound depending on X¹ and X².
 4. Theprocess of claim 1, wherein the compound of Formula I is a compound ofFormula Ia:

or a pharmaceutically acceptable solvate thereof, wherein R¹ is H or F;R^(1′) is H; R² is H, F, or Cl; R^(2′) is H or F; R³ is F or Cl; R⁴ ismethyl or trifluoromethyl; and

represents an (R)-enantiomer or a racemate of the compound of FormulaIa.
 5. The process of claim 4, wherein the compound of Formula I is acompound of Formula Ia′:

or a pharmaceutically acceptable solvate thereof, wherein R¹ is H or F;R^(1′) is H; R² is H, F or Cl; R^(2′) is H or F; R³ is F or Cl; and R⁴is methyl or trifluoromethyl.
 6. The process of claim 1, wherein thecompound of Formula I is a compound of Formula Ib:

or a pharmaceutically acceptable solvate thereof, wherein: R¹ is H or F;R^(1′) is H; R² is H, F, or C1; R^(2′) is H or F; R³ is F or Cl; R⁴ ismethyl or trifluoromethyl; and

represents an (R)-enantiomer or a racemate of the compound of FormulaIb.
 7. The process of claim 6, wherein the compound of Formula I is acompound of Formula Ib′:

or a pharmaceutically acceptable solvate thereof, wherein R¹ is H or F;R^(1′) is H; R² is H, F, or Cl; R^(2′) is H or F; R³ is F or Cl; and R⁴is methyl or trifluoromethyl.
 8. The process of claim 1, wherein thecompound of Formula I is selected from the group consisting of:(R)-(4-fluorophenyl)(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(4-fluorophenyl)(8-methyl-3-(2-methylthiazol-4-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(4-fluorophenyl)(8-methyl-3-(2-(trifluoromethyl)thiazol-4-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)(2,3,4,5-tetrafluorophenyl)methanone;(R)-(3,4-difluorophenyl)(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)(2,3,4-trifluorophenyl)methanone;(R)-(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)(3,4,5-trifluorophenyl)methanone;(R)-(3-chloro-4-fluorophenyl)(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(4-chloro-3-fluorophenyl)(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(4-chlorophenyl)(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(3,4-dichlorophenyl)(8-methyl-3-(5-methylfuran-2-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(8-methyl-3-(2-(trifluoromethyl)thiazol-4-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)(2,3,4,5-tetrafluorophenyl)methanone;(R)-(3,4-difluorophenyl)(8-methyl-3-(2-(trifluoromethyl)thiazol-4-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(8-methyl-3-(2-(trifluoromethyl)thiazol-4-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)(2,3,4-trifluorophenyl)methanone;(R)-(8-methyl-3-(2-(trifluoromethyl)thiazol-4-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)(3,4,5-trifluorophenyl)methanone;(R)-(3-chloro-4-fluorophenyl)(8-methyl-3-(2-(trifluoromethyl)thiazol-4-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(4-chloro-3-fluorophenyl)(8-methyl-3-(2-(trifluoromethyl)thiazol-4-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;(R)-(4-chlorophenyl)(8-methyl-3-(2-(trifluoromethyl)thiazol-4-yl)-5,6-dihydro-[1,2,4]triazolo[4,3-a]pyrazin-7(8H)-yl)methanone;and pharmaceutically acceptable solvates thereof.
 9. The process ofclaim 1, wherein the protecting group PG is selected from the groupconsisting of 2,4-dimethoxybenzyl (DMB), 4-methoxybenzyl (PMB), andtert-butoxycarbonyl (Boc).
 10. The process of claim 9, wherein theprotecting group PG is 2,4-dimethoxybenzyl (DMB).
 11. The process ofclaim 1, wherein the deprotection agent is trifluoroacetic acid (TFA).